Hydroxy decanoyl

CIO-OH 3-Hydroxy decanoyl- M/SCHAD deficiency, MKAT deficiency... 

Helmkamp GM Jr, Rando RR, Brock DJH, Bloch K. B-Hydroxy-decanoyl thioester dehydrase. Specificity of substrates and acetylenic inhibitors. J. Biol. Chem. 1968 243 3229-3231. 

The Type II synthetase of E.coli was the first synthetase studied. The individual proteins have all been isolated, purified and characterized (cf. Volpe and Vagelos, 1973). The synthetase cannot only produce saturated fatty acids but normally makes monounsaturated (principally cw-vaccenic) acids. It does this because of the presence of a -hydroxy-decanoyl-ACP-/3,y-dehydrase which produces cw-3-decenoyl-ACP (precursor of unsaturated acids) instead of ran -2-decenoyl-ACP (converted to saturated acids). The presence of the two de-hydrase enzymes forms a branch point at the Cio level when only the ran5-2-decenoyl-ACP acts as a substrate for enoylreductase. The a 5-3-isomer can be condensed by /3-ketoacyl synthetase so that the double bond is preserved and the production of unsaturated fatty acids is anaerobic (Volpe and Vagelos, 1973). 

Since the enzyme can be totally inactivated by a stoichiometric amount of this acetylene, a single turnover is all that is required for irreversible inhibition to occur. The enormous specificity of this inhibitor in multi-component systems and in vivo was demonstrated in the classic experiments of Kass and Bloch, 5 These experiments showed that B-hydroxy-decanoyl thloester dehydrase was absolutely required for unsaturated fatty acid synthesis in E. coll. 

A classic example of suicide inhibition is that of /3-hydroxy l-decanoyl-dehydrase by 3 -decenoy 1-N-acetylcy steamine.12 The enzyme catalyzes the reaction... 

HRP-catalyzed polymerizations of hydrophobic monomers, A/-(4-hydroxyphenyl)maleimide, 4 -hydroxy-methacrylanilide, and 7V-methacryloyl-ll-aminoun-decanoyl-4-hydroxyanilide, proceeded even in water in the presence of 2,6-di-O-methylated /3-cyclodextrin.36 Formation of water-soluble complexes consisting of the hydrophobic monomers as guest molecules and the cyclodextrin derivative as host was detected. The polymerizable moieties in the polymer were not reacted during the polymerization. 

Isomerization of monoenes occurs in microorganisms for a number of reasons. One of these is because isomerization is an essential step in the synthesis of unsaturated fatty acids by anaerobes. A specific dehydrase (P-hydroxydecanoyl-ACP dehydrase) is capable of both dehydration of a 10-carbon intermediate in a growing fatty acyl chain as well as its isomerization from a trans-2 decanoyl-ACP to a af-d-decenoyl-ACP (32). The anaerobic pathway of unsaturated fatty acid synthesis accounts for 1-6% oleic acid in ruminal microorganisms (33). Other anaerobes, such as Streptococcus pneumoniae, isomerize a trans-2 decanoyl-ACP to a r-3-decenoyl-ACP during fatty acid synthesis without catalyzing the dehydration of P-hydroxy intermediates (34). 

To demonstrate the importance of the hydroxy groups in forming discotic associates compound 4 was esterified with decanoyl-... 

---