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The transglycosylation reaction catalyzed by neopullulanase was analyzed. Radioactive oligosaccharides were produced when the enzyme acted on maltotriose in the presence of [U-14C]glucose. Some of the radioactive oligosaccharides had only alpha-(1----4)-glucosidic linkages, but others were suggested to have alpha-(1----6)-glucosidic linkages. The existence of alpha-(1----6)-glucosidic linkages in the products from maltotriose with neopullulanase was proven by proton NMR spectroscopy and methylation analysis. We previously reported that the one active center of neopullulanase catalyzes the hydrolysis of alpha-(1----4)- and alpha-(1----6)-glucosidic linkages (Kuriki, T., Takata, H., Okada, S., and Imanaka, T. (1991) J. Bacteriol. 173,6147-6152). These facts proved that neopullulanase catalyzed all four types of reactions: hydrolysis of alpha-(1----4)-glucosidic linkage, hydrolysis of alpha-(1----6)-glucosidic linkage, transglycosylation to form alpha-(1----4)-glucosidic linkage, and transglycosylation to form alpha-(1----6)-glucosidic linkage. The four reactions are typically catalyzed by alpha-amylase, pullulanase, cyclomaltodextrin glucanotransferase, and 1,4-alpha-D-glucan branching enzyme, respectively. These four enzymes have some structural similarities to one other, but reactions catalyzed by the enzymes are considered to be distinctive: the four reactions are individually catalyzed by each of the enzymes. The experimental results obtained from the analysis of the reaction of the neopullulanase exhibited that the four reactions can be catalyzed in the same mechanism.

The Saccharomyces cerevisiae chitinase described by Correa et al. (Correa, J. U., Elango, N., Polacheck, I., and Cabib, E. (1982) J. Biol. Chem. 257, 1392-1397) has been cloned and sequenced. Analysis of the derived amino acid sequence suggests that the protein contains four domains: a signal sequence, a catalytic domain, a serine/threonine-rich region, and a carboxyl-terminal domain with high binding affinity for chitin. Most of the enzyme produced by cells is secreted into the growth medium and is extensively glycosylated with a series of short O-linked mannose oligosaccharides ranging in size from Man2 to Man5. Chitinase O-mannosylation was further examined in the temperature-sensitive secretion mutants sec18, sec7, and sec6. Oligosaccharides isolated from chitinase accumulating in cells at the nonpermissive temperature revealed Man1 and Man2 associated with the sec18 mutant. sec6 and sec7 accumulated Man2-Man5 with a higher proportion of Man5 relative to the secreted protein. A significant amount of chitinase is also found associated with the cell wall through binding of COOH-terminal domain to chitin. Disruption of the gene for the enzyme leads to a defect in cell separation but does not substantially alter the level of cellular chitin.

Primary structural studies have been carried out on the light chain of a homogeneous rabbit antibody to Group C streptococcal carbohydrate. Approximately 20 g of this antibody were obtained by multiple exchange transfusions at the peak of the antibody response. The isolated antibody was homogeneous by several antigenic and chemical criteria. The light chain was isolated and modified, and then digested with alpha-chymotrypsin or thermolysin. The resulting peptides were isolated by gel filtration, paper electrophoresis, and paper chromatography. The amino acid sequences of these peptides were determined by Edman degradation plus dansylation. This supplied sufficient information to assign approximately 90 percent of the residues in the chain. The destruction of tyrosine during acid hydrolysis of peptides which had been eluted from a paper chromatogram was investigated. This destruction is due to inpurities in the paper which contaminate the peptides. Prevention of such destruction can be achieved by predevelopment of the paper with 1 N NH4OH prior to paper chromatography.

The adenovirus hexon protein has been carboxymethylated with 14C-labeled iodoacetate. After treatment with CNBr, the peptide mixture was fractionated into fragments with seven size classes by exclusion chromatography. Large fragments were further purified by CM-cellulose chromatography in urea, and small fragments were purified by high voltage paper electrophoresis. Amino acid sequences of pure fragments have been determined by combined use of sequenator-based direct degradations, and of manual t-dimethylaminonaphthalene-1-sulfonyl-monitored Edman degradations subsequent to enzymatic redigestions. Fractionations are given, the primary structures of 22 CNBr fragments containing a total of 677 residues are reported, and the analytical aspects of the structural properties are considered.

1, 2-Cyclohexanedione reacts specifically with the guanidino group of arginine or arginine residues at pH 8 to 9 in sodium borate buffer in the temperature range of 25-40 degrees. The single product, N-7, N-8-(1,2-dihydroxycyclohex-1,2-ylene)-L-arginine (DHCH-arginine) is stable in acidic solutions and in borate buffers (pH 8 to 9). DHCH-Arginine is converted to N-7-adipyl-L-arginine by periodate oxidation. The structures of the two compounds were elucidated by chemical and physicochemical means. Arginine or arginyl residues can be regenerated quantitatively from DHCH-arginine by incubation at 37 degrees in hydroxylamine buffer at pH 7.0 FOR 7 TO 8 hours. Analysis of native egg white lysozyme and native as well as oxidized bovine pancreatic RNase, which were treated with cyclohexanedione, showed that only arginine residues were modified. The utility of the method in sequence studies was shown on oxidized bovine pancreatic ribonuclease A. Arginine modification was complete in 2 hours at 35 degrees in borate buffer at pH 9.0 with a 15-fold molar excess of the reagent. The derived peptides showed that tryptic hydrolysis was entirely limited to peptide bonds involving lysine residues, as shown both by two-dimensional peptide patterns and by isolation of the resulting peptides. The stability of DHCH-arginyl residues permits isolation of labeled peptides.

Carboxypeptidase Y from bakers' yeast is a diisopropyl phosphorofluoridate (DFP)-sensitive enzyme. The inactivation by [32P]DFP is accompanied by the formation of 1 mole of labeled serine per mole of enzyme. A 15-residue 32P-labeled (*) peptide has been isolated from a peptic digest and shown to have the sequence His-Ile-Ala-Gly-Glu-Ser*-Tyr-Ala-His-Gly-Tyr-Ile-Pro-Val-Phe. The reaction of the serine residue with DFP is blocked by the presence of p-hydroxymercuribenzoate, which also inactivates the enzyme. The single —SH group of the protein may be near the active center of the enzyme, but the —SH group is not available to iodoacetate or iodoacetamide in the absence of denaturants. The sequence around the reactive serine residue and the properties of the —SH group contribute to an active site which is quite different from that of DFP-sensitive proteinases such as trypsin, chymotrypsin, or subtilisin.

The histidyl-tRNA synthetase from Salmonella typhimurium was purified to homogeneity by methods described previously. The molecular weight of the native enzyme was determined as 78,000 by high speed equilibrium centrifugation and as 92,000 by gel filtration; a subunit molecular weight of about 40,000 was found by centrifugation in 6 m guanidine HCl, and by sodium dodecyl sulfate gel electrophoresis. The isoelectric point was found to be 5.9 by focusing in polyacrylamide gels; the extinction coefficient at 280 nm was determined to be 80,000 m-1 cm-1. The amino acid composition of the enzyme was determined. In particular, 8 cysteine, 34 lysine, 53 arginine, and 13 histidine residues were found for each molecule, calculated on the basis of an 80,000 molecular weight. Thirteen tryptophan residues were found by absorption spectroscopy in 6 m guanidine HCl; a tyrosine content of 20 residues per 80,000 was estimated. Titration with 5,5'-dithiobis(2-nitrobenzoic acid) reagent showed that 2 cysteine residues were free; titration with 5,5'-dithiobis(2-nitrobenzoic acid) reagent in 8 m urea demonstrated 2 additional cysteine residues. A peptide map of a tryptic digest showed the presence of about 33 ninhydrin staining spots; no NH2-terminal amino acid could be detected. It is inferred that the histidyl-tRNA synthetase in its native state is a dimer, probably composed of identical subunits. The enzyme is stable to storage in 50% glycerol at -20°; at 4° in dilute solution the enzyme slowly loses activity. Gel chromatography shows the appearance of a high molecular weight, inactive form during storage at 4°. This material can be reactivated by incubation with reducing agents.

Platelet responses are inhibited by agents such as prostaglandin E1 that increase the cytoplasmic concentration of cyclic AMP. Inhibition is thought to result from phosphorylation of specific proteins. One protein that becomes phosphorylated is glycoprotein (GP) Ib beta, a component of the GP Ib.IX complex. We have suggested that phosphorylation of GP Ib beta inhibits the collagen-induced polymerization of actin. The aim of the present study was to identify the amino acid(s) in GP Ib beta that is phosphorylated. Purified GP Ib.IX complex was phosphorylated by the catalytic subunit of purified bovine cyclic AMP-dependent protein kinase in the presence of [gamma-32P]ATP. Phosphoamino acid analysis showed that in GP Ib beta, [32P]phosphate was incorporated only into serine and was in a single tryptic peptide. Amino acid sequencing showed that this peptide was from the cytoplasmic domain of GP Ib beta and encompassed residues 161-175. A single serine residue, serine 166, contained the radiolabel. To determine whether the same residue was phosphorylated in intact platelets, GP Ib beta was isolated from 32P-labeled platelets before or after their exposure to prostaglandin E1. In both cases, radiolabel was present in phosphoserine and was in a single tryptic peptide. This peptide was the same as that which was phosphorylated in the purified GP Ib.IX complex, as shown by its identical mobility on two-dimensional tryptic maps, the presence of a positively charged residue in the fourth position, and the presence of the radiolabel in the sixth position of the peptide. This study shows that when cyclic AMP concentrations rise in platelets, the cytoplasmic domain of GP Ib beta is phosphorylated on serine 166, probably by cyclic AMP-dependent protein kinase. We suggest that phosphorylation of this residue may contribute to the inhibitory actions of cyclic AMP by inhibiting collagen-induced polymerization of actin.

The 17 peptides produced by cleavage of actin with cyanogen bromide have been ordered with regard to their sequence in the actin molecule. Tryptic digestion of actin followed by isolation of the methionine-containing "overlap" peptides permitted the unique alignment of most, but not all of the cyanogen bromide peptides. However, maleylation of the actin molecule followed by tryptic digestion and isolation of methionine-containing peptides from maleylated actin permitted the proper placement of the remaining cyanogen bromide peptides. The ordering of cyanogen bromide peptides, together with the amino acid sequence of the individual peptides, constitutes the entire amino acid sequence of rabbit skeletal muscle actin (ELZINGA, M., COLLINS, J. H., KUEHL, W. M., and ADENLSTEIN, R. S. (1973) Proc. Natl. Acad. Sci. U. S. A. 70,2687-2691).