Investigation of the globulins of cotton seeds VIII. Chymotryptic hydrolysis of the 7S-globulin. Isolation and purification of a chymotryptic peptide

Summary From a chymotryptic hydrolyzate of the CM-7S-globulin of cotton seeds we have isolated and characterized in relation to amino-acid composition and N-terminal amino acids 65 homogeneous peptides, 38 of which contain arginine or lysine residues and are overlapping.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 560–566, July–August, 1977.     

The globulins of cotton seeds XII. The structure of the 7S-globulin

Summary 1. The 7S globulin of cotton seeds consists of eight polypeptide chains of two types differing by their contents of carbohydrates and of amide groups.2. On the basis of the results of a study of the amino-acid sequences of the peptides obtained by cleaving the 7S globulin with trypsin and chymotrypsin, its complete primary structure has been put forward.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 687–690, September–October, 1977.     

Investigation of the globulins of cotton seeds VII. Peptides of a triptic hydrolyzate of the 7S-globulin

Summary 1. The peptides of a tryptic hydrolyzate of the 7S-globulin have been isolated and characterized.2. The glycopeptide of subunit II has been isolated and its amino-acid and carbohydrate compositions have been determined.3. It has been shown that the main difference in the subunits of the 7S-globulin consists in the presence of an oligosaccharide in the C-terminal peptide of subunit II.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 556–560, July–August, 1977.     

The globulins of cotton seeds XI. The structure of the chymotryptic peptides of the 7S globulin

Summary The amino-acid sequences of the chymotryptic peptides of the 7S globulin of cotton seeds have been determined.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 682–687, September–October, 1977.     

A study of the globulins of cotton seeds XX. Stability of the quaternary structure of the 11S-globulin

The 11S-globulin has a complex stable quaternary structure in the formation of which three types of subunits participate. The aim of the work was to determine what forces form and stabilize the quaternary structure of this protein. The products of the maleylation and acetylation of the 11S-globulin and also the stability of the native 11S-globulin in the presence of ionic and nonionic detergents were investigated by disk electrophoresis. It was shown that hydrophobic interactions play a deciding role in the formation and stabilization of the quaternary structure of the 11S-globulin.     

The globulins of cotton seeds XIX. Chymotryptic and tryptic peptides of subunit C of the 11S globulin

Summary 1. The structures of 51 chymotryptic peptides isolated from a chymotryptic hydrolyzate of subunit C have been determined.2. The structures of 15 tryptic peptides from a tryptic hydrolyzate of subunit C have been established.3. On the basis of the structures of the peptides, the structure of the molecule of subunit C of the 11S globulin of cotton seeds has been established.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 613–621, September–October, 1978.     

A study of the globulins of cotton seeds XX. Stability of the quaternary structure of the 11S-globulin

The 11S-globulin has a complex stable quaternary structure in the formation of which three types of subunits participate. The aim of the work was to determine what forces form and stabilize the quaternary structure of this protein. The products of the maleylation and acetylation of the 11S-globulin and also the stability of the native 11S-globulin in the presence of ionic and nonionic detergents were investigated by disk electrophoresis. It was shown that hydrophobic interactions play a deciding role in the formation and stabilization of the quaternary structure of the 11S-globulin.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 554–557, July–August, 1979.     

Protease A from cotton seeds. Isolation and purification of the enzyme

Protease A has been isolated in the homogeneous state from dormant seeds of cotton plants of the Tashkent-I variety. A scheme is proposed for the isolation and purification of the enzyme which includes the following stages: extraction of the defatted seeds with 0.1 M phosphate buffer, pH 7.4; precipitation of the protein with ammonium sulfate at 60% saturation; desalting by dialysis; and ionexchange chromatography on a column containing CM- and DEAE-celluloses. The molecular weight of the enzyme has been determined as 60,000. The enzyme efficiently hydrolyzes azocasein and the 7S and 11S reserve proteins of cotton seeds. Its maximum activity appears at pH 6.4–7.4 and a temperature of 35–40°C; it is not activated by sulfhydryl reagents and loses its activity in the presence of diisopropyl phosphorofluoridate. The assumption is made that protease A belongs to the serine type of trypsin-like proteases.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 738–741, November–December, 1986.     

Protease A from cotton seeds. Isolation and purification of the enzyme

Protease A has been isolated in the homogeneous state from dormant seeds of cotton plants of the Tashkent-I variety. A scheme is proposed for the isolation and purification of the enzyme which includes the following stages: extraction of the defatted seeds with 0.1 M phosphate buffer, pH 7.4; precipitation of the protein with ammonium sulfate at 60% saturation; desalting by dialysis; and ionexchange chromatography on a column containing CM- and DEAE-celluloses. The molecular weight of the enzyme has been determined as 60,000. The enzyme efficiently hydrolyzes azocasein and the 7S and 11S reserve proteins of cotton seeds. Its maximum activity appears at pH 6.4–7.4 and a temperature of 35–40°C; it is not activated by sulfhydryl reagents and loses its activity in the presence of diisopropyl phosphorofluoridate. The assumption is made that protease A belongs to the serine type of trypsin-like proteases.     

An investigation of the globulins of cotton seeds. IV

Summary 1. A method has been developed for the preparative separation of the subunits of the 7S globulin of cotton seeds.2. The similarity of the chemical structures of the subunits has been shown by the peptide map method and by a comparison of amino-acid compositions and of N- and C-terminal amino acids. It is suggested that their main difference consists in their carbohydrate contents.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 229–233, March–April, 1976.