Proteins, carrier

Cramer R D III, D E Patterson and J D Bunce 1988, Comparative Molecular Field Analysis (CoMFA). Effect of Shape on Binding of Steroids to Carrier Proteins. Journal of the American Chemical Societ 110 5959-5967. 

We can descnbe the major elements of fatty acid biosynthesis by considering the for mation of butanoic acid from two molecules of acetyl coenzyme A The machinery responsible for accomplishing this conversion is a complex of enzymes known as fatty acid synthetase Certain portions of this complex referred to as acyl carrier protein (ACP), bear a side chain that is structurally similar to coenzyme A An important early step m fatty acid biosynthesis is the transfer of the acetyl group from a molecule of acetyl coenzyme A to the sulfhydryl group of acyl carrier protein... 

Using HSCoA and HS—ACP as abbreviations for coenzyme A and acyl carrier protein respectively write a structural formula for the tetrahedral... 

Formation of malonyl coenzyme A is followed by a nucleophilic acyl substitution which transfers the malonyl group to the acyl carrier protein as a thioester... 

When both building block units are m place on the acyl carrier protein carbon-carbon bond formation occurs between the a carbon atom of the malonyl group and the carbonyl carbon of the acetyl group This is shown m step 1 of Figure 26 3 Carbon-carbon bond formation is accompanied by decarboxylation and produces a four carbon acetoacetyl (3 oxobutanoyl) group bound to acyl earner protein... 

Acetyl and malonyl groups bound to acyl carrier protein... 

Fig. 3. Processing steps of rat and bovine prepro-vasopressin lea ding to the hormone vasopressin and its carrier protein, neurophysin (14). (a) Putative signal peptide (b) vasopressin (c) neurophysin (d) glycopeptide. CHO = carbohydrate.

Using any of the carrier proteins available in highly purified form, eg, TBG or TBPA, a convenient and accurate quantitative determination of and is possible by displacement of radioiodinated or T. This procedure enables their quick determination at low concentrations even in the presence of coundess other substances that occur in body duids (31). In a similar fashion, intact cell nuclei or solubilized proteins from rat fiver cell nuclei, which display high affinities for thyroid hormones, especially T, have been used to establish relative binding affinities of many thyromimetic compounds (7). 

Standardization and Testing". RequHemeats are geaerally specified within Hceases Hi the United States, and include a variety of Hi-process tests to assess purity, safety, and potency of the iadividual components and potency and safety of the final product. Potency is standardized by determining the size of the conjugate and the quantitative amount of saccharide that is bound to the carrier protein. General safety and immunogenicity is assessed Hi animals. 

Biosynthesis of coen2yme A (CoA) ia mammalian cells incorporates pantothenic acid. Coen2yme A, an acyl group carrier, is a cofactor for various en2ymatic reactions and serves as either a hydrogen donor or an acceptor. Pantothenic acid is also a stmctural component of acyl carrier protein (AGP). AGP is an essential component of the fatty acid synthetase complex, and is therefore requited for fatty acid synthesis. Free pantothenic acid is isolated from hver, and is a pale yeUow, viscous, and hygroscopic oil. 

RD Cramer III, DE Patterson, JD Bunce. Comparative molecular field analysis (CoMFA). 1. Effect of shape on binding of steroids to carrier proteins. J Am Chem Soc 110 5959-5967, 1988. 

S-Hexadecanoyl acyl Carbon Acyl carrier Oxidized form Water carrier protein dioxide protein of coenzyme... 

By analogy to the intermediates given in steps 1-4 of Figure 26.3, write the sequence of acyl groups that are attached to the acyl carrier protein in the conversion of... 

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