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Tryptic and peptic peptides of the L-4 light chain of chicken skeletal muscle myosin were isolated. The amino acid sequences of all the tryptic peptides were determined. The alignment of the tryptic peptides in the protein was deduced from their homology with the primary structure of the A2 (L-4) light chain of rabbit skeletal muscle myosin. The compositions of the peptic peptides confirmed the alignment. Comparing the whole sequence of the L-4 light chain thus established with that of the A2 light chain of rabbit skeletal muscle myosin, 24 amino acid substitutions, were recognized.

The light chain fraction was separated from myosin extracted from chicken cardiac muscle. Two light chain components, L-1 and L-2 in the fraction were isolated by chromatography on a column of DEAE-cellulose (DE-52) in the presence of 4 M urea. After performic acid oxidation, the L-1 chain was digested with trypsin and the resulting peptides were isolated. The amino acid sequences of the peptides were established. The ordering of these tryptic peptides in the L-1 chain was deduced from the amino acid compositions and the partial sequences of peptic peptides from S-carboxymethylated L-1 chain. Comparing the whole sequence of the L-1 chain thus established with that of alkali light chain of rabbit skeletal muscle myosin, 67 amino acid substitutions and two insertions were recognized.

We have previously demonstrated that the two heads of chicken gizzard heavy meromyosin (HMM) in a rigor complex with rabbit skeletal F-actin could be cross-linked by the water-soluble carbodiimide 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide. Here, we report the location of the cross-linked sites in the amino acid sequence of the HMM heavy chain. One of the cross-linked residues was identified as Glu-168 by sequencing the CN1.CN6 cross-linked peptide containing residues 1-77 (CN1) and 164-203 (CN6). This site is located close to the ATP-binding site of HMM. Since the other site was further into the amino acid sequence of CN1, another cross-linked peptide corresponding to residues 53-66 and 145-182 was isolated from the 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide-treated acto-tryptic gizzard HMM digested further by other proteolytic enzymes. The amino acid sequence of this peptide and its cyanogen bromide fragment indicated that the cross-linking occurred between Glu-168 and Lys-65. Our results suggests that these two amino acid side chains are in contact with each other in the acto-gizzard HMM rigor complex and participate in the electrostatic interaction between the two HMM heads bound to F-actin. Based on the head-to-head contact, we propose a three-dimensional model for the attachment of gizzard HMM heads to F-actin.

Frequencies of mutations between reconstructed ancestor and descendant sequences of codons for metazoan globin chains show that natural selection guided protein evolution. Mutations which improved haemoglobin function were accepted at an accelerated rate in the first vertebrates. Rates decelerated after functional opportunities had been exploited.

Three kinds of ATP analogues were synthesized. These ATP analogues can be classified into two conformations, i.e. syn and anti forms with respect to the N-glycosidic bond between adenine and ribose groups of ATP. 3'-O-(N-Methylanthraniloyl)-2-azidoadenosine 5'-triphosphate (MantN2(3)ATP) is recognized as the anti form, as ATP, and the other two, 3'-O-(N-methylanthraniloyl)-8-azidoadenosine 5'-triphosphate (MantN8(3)ATP) and 1,N6-etheno-8-azidoadenosine 5'-triphosphate (epsilon N8(3)ATP) are both syn forms. Mant and etheno groups are both fluorescent which allows detection of their binding to proteins. The photochemical binding of azido groups in ATP analogues to the myosin active site, examined in the presence and absence of ATP, showed that all the analogues bound to the site of myosin ATPase. These analogues also acted as substrates of the ATPase and were hydrolyzed in the active site, as judged by competitive inhibition of the ATPase and by their ATPase activities. Of these analogues, MantN2(3)ATP is very similar to ATP in divalent-cation dependence of its hydrolysis rate and in its ability to trap ADP in the active site with vanadate, while the other two are different from ATP in these respects. The photochemical binding sites of ATP analogues were localized by gel electrophoresis of trypsinized myosin ATPase with photocross-linked ATP analogues and/or by isolating the modified peptides. MantN2(3)ATP was found in the 23-kDa fragment which has a structure common to ATP-binding proteins, i.e. Gly-Xaa-Xaa-Gly-Xaa-Gly-Lys-Thr. Mant N8(3)ATP was found in a region of the 20-kDa fragment where actin is reported to attach.

The sequence of the NH2-terminal 808 amino acid residues of chicken pectoralis muscle myosin head was determined. Three characteristic 20-, 23-, and 50-kDa fragments were isolated from a digest of myosin subfragment 1 (S1) by gel filtration on a Sephadex G-100 column in the presence of 5 M guanidine hydrochloride, followed by anion-exchange chromatography on a QAE-Sephadex A-50 column in the presence of 8 M urea. The fragments were sequenced completely by conventional methods. Peptides overlapping the 23- and 50-kDa fragments and also overlapping the 50- and 20-kDa fragments were obtained by cleaving S1 with cyanogen bromide. Comparison of the 23-kDa and 50-kDa sequences with that of the overlapping peptide indicated that no additional amino acid exists between the 23- and 50-kDa fragments and that 5 amino acids exist between the 50- and 20-kDa fragments of S1. Methylated amino acid residues were found at four positions: epsilon-N-monomethyllysine at position 35, epsilon-N-trimethyllysine residues at 130 and 550, and 3-N-methylhistidine at 754.

Gene phylogenetic trees were constructed by the maximum parsimony method for various sets of ninety six globin chain amino acid sequences spanning plant and animal kingdoms. The method, executed by several computer programs, constructed ancestor and descendant globin messengers on tree topologies which required the least number of nucleotide replacements to account for the evolution of the globins. The human myoglobin-hemoglobin divergence was traced to a gene duplication which occurred either in the first vertebrates or earlier yet in the common ancestor of chordates and annelids, the alpha-beta divergence to a gene duplication in the common ancestor of teleosts and tetrapods, the gamma divergence from typical beta chains to a gene duplication in basal therian mammals, and the delta separation from beta to a duplication in the basal catarrhine primates. Evidence was provided by the globin phylogenies for the hominoid affinities of the gibbon and the close phyletic relationship of the African apes to man. Over the period of teleos-tetrapod divergence the globin messengers evolved at an average rate of 18.5 nucleotide replacements per 100 codons per 108 years, a faster rate than most previous estimates. Very fast and very slow rates were encountered in different globin lineages and at different stages of descent, reducing the effectiveness of globins as molecular clocks. Rates increased with gene duplication and decreased after selection discovered useful specializations in the products of genes which had previously been freer to accept mutations. The early eutherian radiation was characterized by rapid rates of globin evolution, but the later hominoid radiation by extremely slow rates. This pattern was related to more complicated grades of internal organization evolving in human ancestors. The types of nucleotide replacements in the globin messengers over the long course of globin evolution did not seem indicative of any special mutational mechanisms.

Three computer programs applied to data from phylogenetic trees and protein polymorphism can be used to find the rate of molecular evolution of different species. It can be shown that this is slower for higher primates than for other mammals.

From the result of a fundamental dietetical study on albino rats, it was known that a diet in which animal protein (casein or fish meal) and soybean protein were mixed at the rate of 9: 3 was more efficient than a diet composed of.either one of them. One of the reasons for this higher efficiency is attributable to a supplementation effect of essential amino acids, especially of methionine and tryptophan, but it consists in yet unknown factors that the addition of soybean protein is unexpectingly effective.

In order to study the lipotropic and toxic actions of DL-methionine, rats of SD strain were divided into 3 groups and were maintained for 22 days on diets prepared by adding 10%, 5% or 0% DL-methionine respectively to a basal diet containing 10% casein and 30% fat. The effect of supplement on weight change, crude fat contents of the liver, and histopathologic changes in livers and kidneys were investigated.The rats in the 10% group showed a rapid weight decrease, and died successively after the 4th day. Those in the 5% group also showed a weight decrease, but were alive throughout the period of the experiment.In both 10% and 5% groups, the crude fat contents were equal with those of the normal groups, but the liver and kiney exhibited a remarkable fatty degeneration by the probable intoxication.

The light chain fraction was separated from chicken gizzard muscle myosin. After S-carboxymethylation or performic acid oxidation, two light chain components (20 000-Mr and 17 000-Mr chains) were isolated by chromatography on a column of DEAF-cellulose in the presence of 4 M urea. Tryptic peptides of the S-carboxymethylated 20 000-Mr chain were isolated, and their sequences were determined. The alignment of these tryptic peptides in the chain was deduced from the amino acid compositions and from the partial sequences of peptic peptide of the oxidized protein. The established sequence consists of 171 amino acids and its calculated molecular weight is 19692. Comparing the sequence with those of L-2 chains from chicken and rabbit skeletal muscle myosins, 81 and 78 amino acid substitutions were recognized, respectively, including insertions and/or deletions.

An antibody was developed against a 23-kDa fragment of myosin which contains a part of the ATP-binding site, and applied to skinned muscle fibers. The antibody abolished active tension generation of the fibers, but did not block their assumption of a rigor state nor their release from this state by ATP. The primary amino acid sequence of the antigenic site on the fragment was found to be the region containing residues 77-80. This sequence region is predicted to have interesting secondary structures, and is distinct from the proposed ATP-binding site. We discuss the possibility that the region is responsible for the energy-transducing step in muscle contraction.

以上の実験成績からD-及びL-Pyrroglutamin酸注射群は体重では寧ろ対照群よりも増加する傾向を示し, 検尿肝臓病理所見は共に著しい差を示さないことが認められた。従つてこの程度の量即ちRatte 1匹当り43mgを29日間に腹腔内注射 (初め約2週間は毎日5～6mg/kg, 次の2週間は10～12mg/kg) では無害であり, 日常我々の食品中に混入して摂取されるPyrroglutamin酸の影響は考慮しなくてもよいと思われる。

activating regulator mutations. Analysis of amino acid sequence data from the alpha and beta hemoglobins and myoglobins suggests that the gene lineages deviate relatively little from established species relationships, and that most contemporary gene pairs in this phylogenetic system may be regarded as orthologous (split at the time of speciation) rather than paralogous (split prior to speciation). It also appears that as the statistical sample of orthologous sequence sites becomes greatly enlarged by tandem alignment of enough different types of protein chains, the parsimony reconstruction based strictly on minimal nucleotide replacement length will itself reveal the correct cladogram for the set of contemporary species. [Phylogeny reconstruction; parsimony methods; globin sequences; gene phylogeny; species phylogeny.]