Biomaterial Database

Assignment of disulfide bonds in the beta subunit of human chorionic gonadotropin. 1981

T Mise, and O P Bahl

The assignment of five disulfide bonds in the alpha subunit of human chorionic gonadotropin (hCG) using partial reduction and S-[14C]carboxymethylation has been reported earlier (Mise, T., and Bahl, O. P. (1980) J. Biol. Chem. 255, 8516-8522). Employing a similar approach, we have determined the locations of six disulfide bonds in hCG-beta. Two partially reduced and S-[14C]carboxymethylated hCG-beta derivatives, DS1.4-hCG-beta and DS3.4-hCG-beta in which on the average 1.4 and 3.4 disulfide bonds were modified, respectively, were prepared. The 14C-labeled derivatives were then completely reduced and S-carboxymethylated with nonradioactive iodoacetic acid and subjected to hydrolysis with trypsin. The radioactive peptides were purified by gel filtration and high voltage paper electrophoresis. The tryptic peptides containing two or more S-[14C]carboxymethylcysteines were further degraded using various proteolytic enzymes such as thermolysin, carboxypeptidase A and Y, cathespin C, and subtilisin to obtain individual S-[14C]carboxymethylcysteine-containing peptides. From the specific radioactivities of S-[14C]carboxymethylcysteines in DS3.4-hCG-beta, four out of six disulfide bonds, 9-90, 26-110, 34-88, and 93-100 were assigned. Similar data from DS1.4-hCG-beta gave the locations of the other two disulfide bonds, 23-72 and 38-57, while confirming the locations of four disulfide bonds derived from the radioactivity distribution in DS3.4-hCG-beta. Thus, all six disulfide bonds in hCG-beta have been located. The results of controlled reduction and S-[14C]alkylation also indicate that disulfide bond 93-100 is the most reactive, followed by disulfide bond 26-110, and that the least reactive among all is 34-88.

UI	MeSH Term	Description	Entries
D007461	Iodoacetates	Iodinated derivatives of acetic acid. Iodoacetates are commonly used as alkylating sulfhydryl reagents and enzyme inhibitors in biochemical research.	Iodoacetic Acids,Acids, Iodoacetic
D010084	Oxidation-Reduction	A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).	Redox,Oxidation Reduction
D010446	Peptide Fragments	Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.	Peptide Fragment,Fragment, Peptide,Fragments, Peptide
D011487	Protein Conformation	The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).	Conformation, Protein,Conformations, Protein,Protein Conformations
D004220	Disulfides	Chemical groups containing the covalent disulfide bonds -S-S-. The sulfur atoms can be bound to inorganic or organic moieties.	Disulfide
D006063	Chorionic Gonadotropin	A gonadotropic glycoprotein hormone produced primarily by the PLACENTA. Similar to the pituitary LUTEINIZING HORMONE in structure and function, chorionic gonadotropin is involved in maintaining the CORPUS LUTEUM during pregnancy. CG consists of two noncovalently linked subunits, alpha and beta. Within a species, the alpha subunit is virtually identical to the alpha subunits of the three pituitary glycoprotein hormones (TSH, LH, and FSH), but the beta subunit is unique and confers its biological specificity (CHORIONIC GONADOTROPIN, BETA SUBUNIT, HUMAN).	Chorionic Gonadotropin, Human,HCG (Human Chorionic Gonadotropin),Biogonadil,Choriogonadotropin,Choriogonin,Chorulon,Gonabion,Human Chorionic Gonadotropin,Pregnyl,Gonadotropin, Chorionic,Gonadotropin, Human Chorionic
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D000596	Amino Acids	Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins.	Amino Acid,Acid, Amino,Acids, Amino
D014108	Tosylphenylalanyl Chloromethyl Ketone	An inhibitor of Serine Endopeptidases. Acts as alkylating agent and is known to interfere with the translation process.	Chlorophenyltosylamidobutanone,TPCK,Tosylphenylalanyl Chloromethane,Chloromethane, Tosylphenylalanyl,Chloromethyl Ketone, Tosylphenylalanyl,Ketone, Tosylphenylalanyl Chloromethyl