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Peptide B, the N-terminal fragment of thioredoxin obtained by cyanogens bromide treatment was aminoethylated and digested with pepsin. Eight peptides were separated by high voltage paper electrophoresis and chromatography and characterized with respect to amino acid sequence. The results account for all 37 residues peptide B. The N-terminal sequence of peptide B was determined as: Ser-Asp-Lys-Ile-Ile-His-Leu-Thr-Asp-Asp-Ser-Phe. [ABSTRACT FROM AUTHOR]

Tryptic and chymotryptic digestion of peptide B, the N-terminal fragment obtained by cyanogen bromide cleavage of thioredoxin, provided the information required to determine the contiguity of the peptic fragments studied previously. The complete sequence of the 37 residues of peptide B could thus be established. Peptide B contains the active center of thioredoxin. Its amino acid sequence was found to be: -Trp-Ala-Glu-Trp-Cys-Gly-Pro-Cys-Lys-Met-. This sequence supports earlier conclusions dragon from fluorescence studies of thioredoxin, which indica ted a close relationship between one or both tryptophan residues and the disulfide bridge of the active site. Peptide maps of the tryptic digests of carboxymethylated thioredoxin and of the two cyanogen bromide fragments are described. Amide nitrogen analyses of thioredoxin and the two cyanogen bromide fragments demonstrate that all seven amide groups of thioredoxin are localized in the C-terminal fragment (peptide A). [ABSTRACT FROM AUTHOR]

A purified glycoprotein with blood-group-A specificity, was digested with insoluble pronase to give a serologically active product enriched in peptide-bonded serine and threonine residues; this was degraded with 0.25 M sulphuric in glacial acetic acid for 24 h. The resultant N-acetylgalactosaminyl-peptide were hydrolysed with 0.2 M hydrocholoric acid for 24 h at 110 °C. fractionation of the products on Sephadex G-10, followed by preparative separation on amino-acid analyzer and paper electrophoresis at pH 1.9 yielded the following homogeneous oligopeptides; one tripeptide with the N-terminal sequence Thr-Thr-Ser, three tetrapeptides with the sequences, Thr-Ser-Thr-Ser, Thr-Pro-Thr-Ser and Pro-Thr-Thr-Ser, one pentapeptide with the sequence Thr-Pro-Thr-Ser, one hexapeptide with the sequence Pro-Thr-Thr-Thr-Pro-Ser and one heptapeptide with the sequence Ala-Pro-Thr-Thr-Ser-Gly-Ser. Galactosamine was present in several of these fragments and the hexapeptide and heptapeptide both contained sufficient of this sugar for all the serine and threonine residues to be glycosylated. The following five tetrapeptides sequences were deduced from mixtures of two peptides which differed by the amino-acid substituent at only one position in the chain; Pro-Thr-Ala-ser, Thr-Thr Pro-Ser, thr-Thr-Ala-Ser, Ser-Pro-Thr-Ser, and Ser-Ala-Thr-Ser. A tripeptide mixture which differed only in the nature of the third amino acid yielded the following three tripeptide sequences: Pro-Thr-Ser, Pro-thr-Ala. These peptides do not indicate a clearly defined amino-acid sequence surrounding the glycosylated hydroxy amino acids but establish that in the human blood-group-specific glycoproteins there is close packing of the threonine in the region of the peptide moiety carrying the carbohydrate chains. [ABSTRACT FROM AUTHOR]

Peptide studies on two acidic proteins, A1 and A2, from 50-S ribosomes of Escherichia coli indicate a closely related primary structure. 1. Amino acid compositions of the tryptic peptides of the two proteins are identical, with exception of the amino terminal peptide. 2. The N-terminal amino acid sequence of A2-protein is Ser-Ile-Thr-Lys, while that of A1-protein is N-acetyl-Ser-Ile-Thr-Lys. 3. The estimated number of 120 amino acid residues in each polypeptide chain is consistent with the physical molecular weight estimate. 4. In 50% of the polypeptide chains, in both A1- or A2-protein, a specific lysine residue is replaced by ε-N-monomethyl-lysine. [ABSTRACT FROM AUTHOR]

Previous reports [1-5], we have described some of the features of the primary structure of bovine αs1-casein. In the present work, the complete amino acid sequence has been established and the salient features of this phosphoprotein have been discussed. In the polyeptide chain, the region containing the phosphopeptides Tm1 (T1-T2), Tm1T2 and Tm1T1 [1,4,5], had only been slightly studied as yet. Because of the difficulties encountered in the breakdown of these phosphopeptides, hydrolysis with endopeptidases and exopeptidases were performed on both native and dephosphorylated peptides. It was confirmed that peptide Tm1T2 contains three hydroxy-amino acids (2 Ser, 1 Thr), but, instead of three [1], two phosphorus atoms were found with purified preparations. Partial acid hydrolysis and dephosphorylation using an orthophosphoric-monoester phosphohydrolase indicate that the two seryl residues m this peptide are O-phosphorylated. The remaining gap in the sequence of the central part of peptide Tm1T2 was bridged by studying two fragments obtained by papain digestion of the dephosphorylated preparation. Instead of four serines, postulated earlier from the results of the amino-acid composition of peptide Tm1T1 [1], five were shown to be present after detailed analysis of the fragments. Since the five phosphate groups could be ready removed by an orthophosphoric-monoester phosphohydrolase, the five seryl residues could be O-phosphorylated. The fragments obtained after hydrolysis with thermolysin of both native and dephosphorylated peptide Tra1T1 were further degraded using classical methods for the determination of the amino acid sequence. In the light of all the results obtained on this phosphoprotein (αs1-casein B), the total number of amino acid residues has been corrected to 199, instead of 198, as reported previously [1-5], and the molecular weight has been calculated to be 23616. The following amino-acid composition; Asp7, Asn8, Thr5, Ser8, SerP8, Glu25, Gln14, Pro17, Gly9, Ala9, Val11, Met5, Ile11, Leu17, Tyr10, Phe8, Lys14, His5, Trp2, Arg6, indicates that there is a higher number of acidic than basic residues in this protein. On the basis of the intrinsic dissociation constants of titratable groups in proteins [6], the negative net charge of the molecule was estimated to be 22 at pH 6.5 and 28 at pH 8.6. Since Bigelow's parameter for thc average hydrophobicity [7] of this protein is 1170, it could be considered to be a hydrophobic protein The high amount (8.5%) and uniform distribution of prolyl residues indicate that this protein has limited structuralcoiling possibilities. The polypeptide chain contains three hydrophobic regions, viz. 1-44, 90-113 and 132-199. The first two are characterized by the fact that basic residues predominate over acidic residues. The third region, where most of the aromatic residues are located, contains very few basic residues and is therefore of more acidic character. Two regions, 45-89 and 114-131, are hydrophilic. The former contains more than half of the total acidic residues, in particular seven of the total eight phosphoseryl residues. Another remarkable feature is the concentration of amino acids with carboxylic side chains, particularly glutamic acid, in the vicinity of two clusters of phosphoseryl residues. It may be noticed that the phosphoseryl residues m αs1-casein are arranged m a manner similar to those in β-casein [8]. In particular, in αs1-casein, the 62-70 region containing four phosphoseryl residues, is similar to the 13-21 region in β-casein [8]. It is interesting to point out that ail but one of the phosphoseryl residues always occur m position n with relation to a glutamyl or a phosphoseryl residue, which is in position n + 2. From this, it would appear that there is an enzymatic phosphorylation of the polypeptide chum (carried out by a phosphoryl kinase which may require a negative charge in the phosphorylation site) rather than a direct incorporation of phosphoserine into the polypeptide chain during protein synthesis. The location of the amino-acid substitutions that characterize the αs1-Casein D and the β-casein C variants has provided evidence for an enzymatic phosphorylation of casein [9]. The problem of the phosphorylated sites in αs1- and β-caseins will be discussed in a forthcoming paper. The repeating amino-acid sequences located in the two regions of αs1-casein, viz. 70-84 and 110-125, are also of interest. The primary structure of αs1-casein given here is that of the genetic variant B. The three other variants A, C and D have also been studied. The C and D variants differ from the B variant by the substitutions of Gly/Glu in position 192 [10] and ThrP/Ala in position 53 [9], respectively. The A variant is characterized by a deletion of thirteen amino-acid residues from position 14 to position 26 in the hydrophobic NH2-terminal part of the polypeptide chain [11]. Because of this deletion, there m an important change in the physico-chemical properties of αs1-casein [12, 13]. Some important features of the amino-acid-sequence determination should be noted. Firstly, the great value of maleic anhydride as a reversible-blocking reagent for amino groups of proteins [14], and the usefulness of thermolysin as a specific enzyme for degrading polypeptides [15]. Secondly, the difficulties encountered during the study of the phosphopeptides: these peptides were difficult to purify since they have similar anionic characters and only react slightly with ninhydrin during paper revelation; other difficulties have been the high destruction of phosphoserine during hydrolysis with HCl 5.7 N, the poor yield in the substractive Edman degradation when the NH2-terminal residue is a phosphoserine, and the failure of endopeptidases and exopeptidases to split off peptide bonds that are close to phosphate groups. Fortunately, alkaline phosphatase has proved to be a useful tool for removing phosphate groups, thus avoiding most of these difficulties. Since the amino-acid sequence of αs1-casein is now known, the degradation of this protein by coagulating and other proteolytic enzymes during cheese ripening may be studied. In particular, bitter peptides originating from αs1-casein may be located. As we have already briefly noted [4], it is obvious that one of the three bitter peptides isolated by Matoba et al. [16] from a tryptic hydrolysate of whole casein, was the segment 23-34 of the polypeptide chain of αs1-casein. In addition, the knowledge of the primary structure will be of help in understanding many aspects of the relations between structure and physical properties in this phosphoprotein. [ABSTRACT FROM AUTHOR]

The isolated α-chain of sea anemone collagen was cleaved at methionyl residues with cyanogen bromide. Eleven unique peptides were isolated by ion-exchange and molecular-sieve chromatography, eight of them in approximately equimolar amounts. Characterization of the eleven peptides with regard to amino-acid composition and molecular weight demonstrated that the isolated peptides account for all of the amino acids and for the molecular weight of the α-chain within experimental error. Since the molecule of sea anemone collagen contains ten methionyl residues, the data of the present paper confirm earlier analytical and preparative results that this invertebrate collagen is made up of three identical α-chains. In comparison with known collagens, on the basis of quantitative and qualitative features of amino-acid compositions, the cyanogen bromide peptides of sea anemone collagen indicate genetical relationship of sea anemone collagen to basement membrane collagen. [ABSTRACT FROM AUTHOR]

The amino acid sequence of the porcine vasoactive intestinal octacosapeptide is His -Ser -Asp -Ala -Val -Phe -Thr -Asp -Asn -Tyr -Thr -Arg -Leu -Arg -Lys -Gln -Met -Ala -Val -Lys -Lys -Tyr -Leu -Asn -Ser -Ile -Leu -Asn -NH2. Its amino acid residues 1, 2, 6 and 7, counted from the N-terminus, are Identical to those in the corresponding positions in both porcine glucagons and secretin. The residues in positions 3, 12, 13, 14, 23 are identical to those in secretin, but not in glucagons, and position 10 is occupied by a tyrosyl and position 28 by an asparanginyl residue, like in glucagons but not in secretin. If in addition to identical amino acid residues also chemically similar residues, such as isoleucine in position 26 of the octacosapeptide, as compared to leucine in secretin and glucagons, are taken into consideration then the similarity between these three polypeptide is still more evident. At a more remote level there is some structural resemblance also between these peptides and the other four peptides from the intestinal wall, cholecystokinin-pancreozymin, motilin, the gastric inhibitory peptide and substance P, the structures of which are known. The elucidation of the structure of the octacosapeptide was facilitated by the finding that pancreatic kallikrein preferentially cleaved only one of the three bonds in its X-terminal cyanogen bromide heptadecapept.ide that are susceptible to cleavage with trypsin. [ABSTRACT FROM AUTHOR]

The primary structure of porcine luteinizing hormone α-subunit was established by determination of the amino acid sequence of its tryptic peptides, which were aligned by homology with the known sequence of ovine luteinizing hormone α-subunit. Its polypeptide chain is shorter by six amino acid residues at its amino-terminus, when compared to the ovine α-subunit. Furthermore four amino acid replacements are observed in the porcine as compared with the ovine chain. Heterogeneity of both carbohydrate prosthetic groups of porcine luteinizing hormone α-subunit is indicated by the different sugar compositions of the glycopeptides isolated in the course of this work. [ABSTRACT FROM AUTHOR]

The αA2 chain of bovine α-crystallin was fragmented by means of cyanogen bromide treatment and by tryptic, chymotryptic and thermolytic digestions. Twenty tryptic peptides were obtained from the S-aminoethylated αA2 chain, accounting together for the complete sequence. The direct Edman degradation and the dansyl-Edman technique were used to determine the sequences of the tryptic peptides. The order of the tryptic peptides was deduced from overlapping peptides obtained by cyanogen bromide treatment, tryptic digestion of the maleylated chain and chymotryptic and thermolytic digestion of the S-aminoethylated chain. The sequence of the αA2 chain comprises 173 residues and corresponds to a molecular weight of 19832. [ABSTRACT FROM AUTHOR]

Commercial lima bean inhibitor was fractionated into four apparently homogeneous components as previously described by Jones, Moore and Stein in 1963. Reduced and alkylated component IV was hydrolyzed with trypsin and the resulting peptides were separated by ion exchange chromatography on Dowex 50 X2 or gel filtration on Bio-Gel P-6. Where necessary, further purification of the peptides was carried out by paper chromatography, paper electrophoresis or a combination of both. Seven peptides were obtained in pure form and their compositions are reported here. The amino acid sequence of six of these peptides was determined, using classical methods. When allowance is made for the occurrence of two homologous peptides, presumably resulting from heterogeneity m the original protein preparation, the tryptic peptides isolated, account for the complete composition of the protein. In an attempt to obtain overlapping sequences the tryptic digest was also performed on the reduced, alkylated and guanidinated protein. Five tryptic peptides, including one containing homoarginine as the carboxy-terminal residue, were isolated in pure form from the digest; their amino acid compositions are reported. [ABSTRACT FROM AUTHOR]

The biosynthesis of melittin, the main toxin of bee venom, was studied in vivo by feeding radioactive amino acids to honey bees. Extracts from venom glands were analyzed for the presence of labeled melittin and other components. Radioactivity was first incorporated into another peptide which is considered to be a precursor of melittin. This conclusion is based on the observed labeling kinetics demonstrating the transient formation of this peptide. Furthermore, the structural similarity between melittin and this component could be established. Evidence is presented showing that it differs from melittin at the amino end. The precursor peptide could not be detected in the ejected venom. [ABSTRACT FROM AUTHOR]

The study of the structure of the peptides arising from native, oxidized or reduced and maleinized bovine growth hormone on incubation with trypsin, ehymotrypsin and pepsin is reported. The data obtained permitted the assembly of a unique sequence of amino acids for the poly-peptide chain of the protein. Various corrections and one addition to the sequence previously communicated are made. [ABSTRACT FROM AUTHOR]

From the tryptic hydrolyzate of pig immunoglobulin &kappa-chains 6 cystine-containing fragments were isolated. Amino acids analysis showed that they contained 37-70 amino acid residues and were of a variable nature. There exists a linear relationship between the specific electrical charge of the fragment and the ionic strength of the buffer by which the fragment is eluted from a column of QAE-Sephadex. Fragments, the disulfide bond of which was split by oxidative sulfitolysis, were split by thermolysin and the hydrolyzates were compared by the method of peptide maps. All the maps of fragments tested contained the peptide Ile-ThrSerCysSSO3-Arg (where CysSSO3 = S-sulfo-cysteine) which represents the vicinity of the half-cystine 24 of pig κ-chains, as shown by us previously. The nature of the peptide maps indicates that the individual fragments originate in the same section of the primary structure of the N-terminal half of the κ-chains. Each of the isolated fragments was a mixture of variants with an identical specific charge but with some amino acid replacements. [ABSTRACT FROM AUTHOR]

The section which represents a part of a larger fragment of the variable part of pig immunoglobulin λ-chains is constituted by two peptides (18 residues and 4 residues)of variable character. These peptides were fractionated and their amino acid sequence determined. At certain positions two to four different amino acids were found. There is a close relation between the found amino acid sequence ... and the amino acid sequence of the corresponding region of human type L Bence-Jones proteins. [ABSTRACT FROM AUTHOR]

Amino acid analyses on thioredoxin reductase indicate the following amino acid composition: Asp65Thr43Ser26Glu60Pro17Gly63Ala58Val32Met12Ileu39Leu53Tyr16Phe18Try2Lys23His18Arg29 (total half-cys)8 (CONH2)59. The enzyme consists of two identical or very similar polypeptide chains joined by noncovalent bonds. This is indicated from experiments employing ultracentrifugation in urea or guanidine hydrochloride, from the analysis of tryptic peptide maps and from quantitative determinations of NH2-terminal amino acids. Carboxymethylation of the enzyme with iodoacetic acid under different conditions showed that each polypeptide chain of the native enzyme contains one disulfide and two free sulfhydryl groups, the latter buried in the enzyme structure. Titration of the enzyme with NADPH under anaerobic conditions demonstrated that the complete reduction of one molecule of enzyme requires four molecules of NADPH. The results indicate that the enzyme contains two redox acceptors in addition to the two molecules of flavin adenine dinucleotide. Evidence is presented that these redox acceptors are identical with the two disulfides of the enzyme. Spectral studies of thioredoxin reductase employing anaerobic titration with substrate did not reveal the formation of a stable red 2-electron intermediate similar to that observed for two other flavoproteins, lipoyl dehydrogenase and glutathione reductase. This finding suggests that the catalytic mechanism for thioredoxin reductase is different from that of lipoyl dehydrogenase and glutathione reductase. [ABSTRACT FROM AUTHOR]

All cysteine-containing peptides of the MOPC 173 (γG2a) monoclonal immunoglobulin were isolated and sequenced, allowing characterization of the twelve intrachain disulfide bonds, and extension of previous work concerning the interchain disulfide budges [3]. Positioning of the various bonds was deduced from homology with the known sequences of the mouse ℵ chains [6,21], MOPC 173 VH region [2], and human γ chains [8], and allowed corroboration of the previous proposed order of the CNBr fragments isolated from the whole molecule [1]. The general pattern of the γG2a, mouse immunoglobulin seems in agreement with the accepted view that this molecule contains two heavy chains and two light chains linked by disulfide bonds, and having intrachain bridges disposed in a strictly linear manner [4,8]. [ABSTRACT FROM AUTHOR]

The partition of alkali cations and anions between an aqueous and an immiscible organic phase has been studied in the absence and presence of neutral and carboxylic ionophores of the valinomycin and nigericin types, respectively. Cation extraction into the organic phase was augmented considerably by the ionophores, and a cation specificity of K≧Rb>Cs≫Na was found for all the neutral ionophores tested. Evidence is given that the actual values of ion specificity are a function of the solvent polarity, especially for valinomycin where an inversion of the K/Rb specificity was observed. The ionophores examined have the following rank order of effectiveness for K extraction into a standard organic phase consisting of 70% toluene-30% n-butanol: valinomycin>18-crown-6≫trinactin>enniatin B≈dinactin>monactin>nonactin. The ion affinity and selectivity data thus obtained have been compared with data previously reported. In a toluene-butanol solvent, extraction of cations in the absence of ionophores occurs as ion pairs. On the other hand, the neutral ionophores extract the cations by the mechanism of complexation, with the lipophilic anions coextracted as free gegenionic species at lower ionophore complex concentrations. When the concentration of extracted cations exceeds 1×10 m, ion pairing between the ionophore complex and the anion occurs, and this tendency increases with increasing concentration and decreasing polarity of the organic phase. Anion pairing with the complexed cations is much less than for the free cations and this effect appears to be due to the larger distance of closest approach of the anion for the complexed cation. [ABSTRACT FROM AUTHOR]

1. The primary sequences of three neurotoxins from the venom of Dendroaspis viridis have been determined. 2. Two of the toxins (72 amino acids, 5 disulphide bridges) differ only in the oxidation of a tryptophan residue. 3. The third toxin contains 60 amino-acid residues and 4 disulphide bridges. 4. The toxins are homologous with other neurotoxins from venoms of the Proteroglyphae. 5. The long toxins are unique in the substitution of a glutamic acid residue for a previously invariant lysine. 6. All three toxins have been shown to prevent neuromuscular transmission by reducing the sensitivity of the muscle membrane to the transmitter, acetylcholine. 7. The toxins all act reversibly at the neuromuscular junction. 8. The toxins did not block sensory nerve terminals. [ABSTRACT FROM AUTHOR]

A chymotrypsin-like endopeptidase has been purified by ion-exchange chromatography, affinity chromatography, and gel filtration. The enzyme preparation is homogeneous in the ultracentrifuge and disc electrophoresis. The enzyme is proved to be free from any other proteolytic activities. The molecular weight of the proteinase as determined with several techniques (ultracentrifugation, gel filtration and electrophoresis without dodecylsulfate) is in the range between 13000–14000; however, by dodecylsulfate gel electrophoresis a molecular weight of 23000 was obtained. The obtained physical constants of hornet chymotrypsin are: sedimentation coefficient s20,w0 = 1.96 ×10-13 s, diffusion coefficient D20,20 = 131 μm² s-1, partial specific volume &vline; = 0.737 ml g-1, frictional ratio ƒ/ƒmin = 1.04, and degree of hydration = 0.1 g per g protein. [ABSTRACT FROM AUTHOR]

The apparent first-order rate constant (kobs) for the deacylation of α-benzamido-transcinnamoyl-chymotrypsin, determined by direct observation at 310 nm, pH 7.9 (kobs = 0.102 s-1; K. Brockelhurst and K. Williamson [1967] Chem. Commun., 666), differs from Kcat determined under the same conditions with [S]0 ... [E]0 (kcat = 0.033 s-1). This result is contrary to other evidence indicating that kcat is a measure of the deacylation rate constant. The discrepancy has been shown to be due to the presence in commercial samples of α-chymotrypsin of impurities which catalyse the deacylation reaction under the conditions used for the determination of kobs ([E]0 [S]0). The impurities, which may be removed from enzyme solutions by gel filtration on Sephadex G-25 or G-50, have been shown to be autolysis products (presumably peptides) of α-chymotrypsin. Catalysis of deacylation results from attack of the free α-amino groups of these peptides on the acyl-enzyme, to give N-α-benzamido-trans-cinnamoyl-peptides. The consequences of these findings must be considered in interpreting any experiment in which deacylation is observed directly at high enzyme concentration, with [E]0 [S]0. Particularly susceptible to error are experiments designed to determine the effect of pH on the deacylation rate constant, and literature results of some such experiments are critically assessed. [ABSTRACT FROM AUTHOR]

The interrelationship of encephalomyocarditis (EMC) virus-specific polypeptides was analysed by comparing their [35S]methionine-labelled tryptic peptides using thin-layer electrophoresis and chromatography. It was found that the peptide patterns of EMC virus is similar to that of polypeptide A, whereas the fingerprint patterns of polypeptides C, D and E are similar to each other but differ greatly from that of A and purified virus. This is consistent with the proposal that polypeptide A is the precursor of the virus capsid proteins, and that polypeptide E is the cleavage product of D and C. The large number of labelled peptides found in the digests of low-molecular-weight proteins G, H, I indicates that they are a mixture of different polypeptides of similar molecular weight generated by the intracellular cleavage of large precursor molecules. [ABSTRACT FROM AUTHOR]

A method for amino acid analysis by double isotope labeling has been developed using ⊃3H-labelled dansyl chloride, and 14C-labelled amino acids as internal standards. As little as 20 pmol of an amino acid can be accurately measured by this method. The amino acid compositions of several peptides, determined using about 50pmol peptide, are reported and compared with the results obtained using conventional high-sensitivity ion-exchange chromatography. The correspondence is very good. The amino acid composition of a tryptic peptide containing the active site disulphide bridge of the lipoamide dehydrogenase component of the pyruvate dehydrogenase multienzyme complex of Escherichia coli has been shown to be identical to that of the corresponding peptide from the 2-oxoglutarate dehydrogenase complex of the same organism. This result is consistent with the view that the lipoamide dehydrogenase components of both complexes have a common amino acid sequence. [ABSTRACT FROM AUTHOR]

The amino acid sequences of two rat C-peptides corresponding to two rat proinsulins have been elucidated. Both C-peptides have 31 amino acids. There are differences in two positions, namely, in position 8 where rat-I has a proline and rat-II an alanine residue, and in position 17 where rat-I has a glutamic acid, rat-II a glycine residue. The additional acidic residue in rat-I C-peptide is counteracted by the additional basic residue in the insulin moiety of rat-I proinsulin (lysine B 29), which provides the two proinsulins with the same net charge at neutral pH. The amino acid sequences are: Glu-Val-Glu-Asp-Pro-Gln-Val-I:Pro/II:Ala -Gln-Leu-Glu-Leu-Gly-Gly-Gly-Pro-I: Glu:/II: Gly-Ala-Asp-Gly- Leu-Gln-Thr-Leu-Ala-Leu-Glu-Val-Ala-Arg-Gln. The rat C-peptides contain threonine and arginine, neither of which is present in the C-peptides of man, pig and ox. A comparison of the 5 sequences shows only 10 identical positions out of 31. [ABSTRACT FROM AUTHOR]

The binding of fluorescein to bovine serum albumin was studied by equilibrium dialysis under various conditions At pH 8.0 and 5°C there are three binding sites with association constants of 2.8 x 104 M-1. Specific labeling of the binding sites using fluorescein-isothiocyanate showed that two of the binding sites are immediately adjacent. The labeled peptides were isolated and the sequence around one of the binding regions was determined revealing the presence of three lysines in this eight amino acid sequence. The binding is mainly caused by hydrophobic interactions and to lesser extent by electrostatic forces. The electrostatic contribution is much less than expected compared with other substances which are bound to bovine serum albumin. This is probably related to the fact that fluorescein is a nonphysiological compound and is "nonspecifically" bound to bovine serum albumin, Studies on binding properties of various peptic fragments of bovine serum albumin were performed. They showed that even slight fragmentation caused a drastic decrease in the ability to bind fluorescein. [ABSTRACT FROM AUTHOR]

The positions of tyrosyl side chains reacting with KI3 without previous urea treatment were identified in the amino acid sequence of porcine glyceraldehyde 3-phosphate dehydrogenase. Tyrosyl groups were labeled with radioactive 131iodine under conditions specific for tyrosine iodination. The labeled protein was digested with trypsins, the radioactive peptides were isolated and their amino acid compositions were determined. From these results the reactive tyrosyl side chains were identified with those at positions 39, 42, 46, 137 and 252 of the sequence determined by Harris and Perham in 1968. [ABSTRACT FROM AUTHOR]

1. A procedure is described for the isolation of ovine growth hormone which involves: extraction of frozen pituitaries with borate buffer at pH 8.4, fractionation by ammonium sulphate precipitation and chromatography on DEAE cellulose. This is followed by removal of various impurities by isoelectric precipitation and by the addition of ethanol. The last step consists in a gel-filtration through a column of Sephadex G-100. 2. The protein obtained is homogeneous judged by free electrophoresis, ultracentrifugation, analytical dialysis and C-terminal amino acid analysis; only polyacrylamide gel electrophoresis reveals two minor components accompanying a major anionic band. It has an isoelectric pH of 6.3 and a weight average molecular weight of 20300. 3. The comparison of the amino acid compositions and of the tryptic peptide maps of ovine and bovine growth hormones indicates great homology between these two proteins. The C-terminal amino acid sequence in ovine growth hormone is as follows: (Phe,Glu,Gly)-AlaSer-Cys-Ala-Phe-OH. [ABSTRACT FROM AUTHOR]