Sikander Aqeel

BIO ALGEBRA OF LIVING ORGANISMS

Aug 15th 2016, 11:17 am

Posted by aqeelsika

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(Bio Mathematical Lab of Sikander Aqeel)

CHAPTER [3] PROTEINS

Proteins

(8/16/2016)

AMINO ACIDS HAVE AN ASYMMETRIC CENTER,

The common amino acids with the normal structure have four substituent’s (R, H, COO-, NH3+) covalently bonded to the a-carbon in the a-amino acid structure, a carbon atom with four different substituent arranged in a tetrahedral configuration is asymmetric and exist in tow enantiomeric form, thus each amino acids (except Cystine, in which R = H and thus two of the four substituent on the a-carbon are hydrogen) exhibits optical isomerism

The absolute configuration for an amino acid is depicted in utilizing the fischer projection to show the direction in space of the tetrahedrally arranged a-carbon substituent, the a-COO- is directed up and back behind the plane of the end and the side chain group is directed down and also behind the plane, the a-H and a-NH3 groups are directed toward the reader, an amino acid held in this project it’s a-NH3 group either to the left or right of a-carbon, by convention, if the a-NH3 is projected to the left, the amino acid has an L absolute configuration, its optical enantiomer with a-NH3 projected toward the right, has a designated D absolute configuration, in mammalian proteins only amino acid of L configuration are found,

The a-H1 and (a-NH3)2 groups are direct toward the reader, its optical enantiomer with a-NH3 projected toward the right, has a designated D absolute configuration for protein, and in mammalian proteins only amino acid of L configuration are found,

As a amino acids in proteins are asymmetric, the proteins into which the amino acids are polymerized also exhibit asymmetric proteins,

DERIVED AMINO ACID CYSTINE

A derived amino acid found in most protein structure is cystine, cystine is formed by the oxidation of two cystine thiol side chain residue, which are joined to form a disulfide covalent bond, the resulting disulfide amino acids is the derived amino acid cystine, within protein covalent disulfide links of cystine formed from cystines, separate from one another in the primary structure, have an important role in stabilizing the folded conformation of proteins, cystines are formed after the free SH-containing cystines are incorporated into the protein of primary structure and after the protein has folded,

Two Cystines,

COO-

NH3- C --H

CH2

H--- C --NH3

COO-

Two cystine = C6H14N2O4 = 181.5

- H2

One cystine

COO-

NH3- C --H

CH2