[Study of the three-dimensional structure of proteins by means of tritium labeling. II. Intramolecular distribution of tritium in the N-terminal part of myoglobin and the tertiary structure of protein]. / Issledovanie prostranstvennoi struktury belkov pri pomoshchi tritievoi metki. II. Vnutrimolekuliarnoe raspredelenie tritiia v N-kontsevoi chasti mioglobina i tretichnaia struktura belka.

The possible use of the method of 3H-label introduction by means of a 3H-atom beam for investigating the three-dimensional structure (surface) of proteins was studied. The intramolecular distribution of tritium in the N-terminal part of 3H-labelled sperm-whale myoglobin was studied. The results obtained are in good agreement with the X-ray analysis data on the polypeptide chain of the protein molecule. The possible use of this method for constructing precise three-dimensional models of polypeptides and proteins is discussed.

[Subtilisin 72: a serine protease from Bac. subtilis strain 72 - an enzyme similar to subtilisin Carlsberg]. / Subtilizin 72-serinovaia proteaza Bac. subtilis shtamm 72, blizkaia subtilizinu Karlsberg.

Subtilisin 72, a serine proteinase secreted by Bac. subtilis strain 72 was purified by covalent chromatography on Sepharose sorbent containing p-(omega-aminomethyl)phenylboronic acid as a ligand. The homogeneity of subtilisin 72 was confirmed by isoelectrofocusing in a thin layer of polyacrylamide gel (pl 8.6). The amino acid composition of this enzyme is different from that of other subtilisins, e. g. subtilisin Carlsberg. The N = terminal amino acid sequence of subtilisin 72 traced up to the 35th residue turned to be the same as that of subtilisin Carlsberg with the exception of the 21st (Tyr) and the 30th (Ile) residues. This very pronounced extent of homology shows that subtilisin 72 is very similar although not identical to subtilisin Carlsberg.

Structural studies on glyceraldehyde-phosphate dehydrogenase from rat skeletal muscle.

The NH2-terminal amino acid sequence of rat skeletal muscle glyceraldehydephosphate dehydrogenase (D-glyceraldehyde-3-phosphate : NAD+ oxidoreductase(physphorylating), EC 1.2.1.12) was determined to be Val-Lys-Val-Gly-Val-Asn-Gly-Phe-Gly-Arg-Ile-Gly-Arg-Leu-Val-Thr-Arg-Ala-Ala-Phe-Ser-Ser-(-)-(-)--Val-Asx-Ile-Val-Ala-Ile. The presence of Asn instead of Asp in position 6 differentiates this enzyme from other glyceraldehyde-3-phosphate dehydrogenases so far sequenced with the exception of the enzymes isolated from liver. The location of Asn in position 6 has been considered as a specific property of liver glyceraldehyde-3-phosphate dehydrogenase (Kulbe, K.D., Jackson, K.W. and Tang, J. (1975) Biochem. Biophys. Res. Commun. 67, 35--42); this suggestion is not sustained by the results of the present investigation. The amino acid composition of the rat skeletal muscle dehydrogenase demonstrates the unusually low histidine content of this enzyme as compared to other mammalian muscle glyceraldehyde-phosphate dehydrogenases.

[Limited proteolysis of bovine pepsin]. / Ogranichennyi proteoliz bych'ego pepsina.

A limited proteolysis of bovine pepsin (EC 3.4.4.1) was carried out. A proteolysis-resistant C-terminal protein fragment containing about 170 amino acid residues was isolated and its N-terminal sequence was established, using Edman's automatic method. It was assumed that the fragment of bovine pepsin isolated, similar to the previosly obtained porcine pepsin fragment, is an independent constituent of the protein molecule.

[Structure of a pepsin fragment containing the functionally important aspartic acid residue]. / Struktura fragmenta pepsina, soderzhashchego funktsional'noi vazhnyi ostatok asparaginovoi kisloty

The structure of B-5 fragment obtained under degradation of pig pepsin by cyanogen bromide is determined. B-5 fragment is a central part of pepsin molecule and it contains 46 amino acids, including a functionally important aspartic residue of the active site of the enzyme. Amino acid sequence of B-5 fragment was established by means of sequenator analysis and of studying the structure of peptides isolated from B-5 fragments.