Isobutyryl system

The mixture of free amino acids is reacted with OPA (Fig. 7-8) and a thiol compound. When an achiral thiol compound is used, a racemic isoindole derivative results. These derivatives from different amino acids can be used to enhance the sensitivity of fluorescence detection. Figure 7-9 shows the separation of 15 amino acids after derivatization with OPA and mercaptothiol the racemic amino acids may be separated on a reversed-phase column. If the thiol compound is unichiral, the amino acid enantiomers may be separated as the resultant diastereomeric isoindole compound in the same system. Figure 7-10 shows the separation of the same set of amino acids after derivatization with the unichiral thiol compound A-isobutyryl-L-cysteine (IBLC). 

The National Library of Medicine has created a vast and patient-oriented healthcare information portal called MEDLINEplus. Within this Internet-based system are health topic pages which hst links to available materials relevant to isobutyryl-CoA dehydrogenase deficiency. Log on to httpvywww.nlm.nih.gov/medlineplus/healthtopics.html To access this system. From there you can either search using the alphabetical index or browse by broad topic areas. Recently, MEDLINEplus hsted the following when searched for isobutyryl-CoA dehydrogenase deficiency ... 

The DEBS 1-TE multienzyme was purified to 90-95% homogeneity and then used in another series of experiments to establish the extent to which alternative starter units could be used by the polyketide synthase [36], Substantial amounts of lactones were obtained in the presence of acetyl-, n-butyryl-, and isobutyryl-CoA, illustrating that the loading didomain exhibits a relaxed specificity for the starter unit (Fig. 10). The utilization of acetyl-CoA and -butyryl-CoA by DEBS 1 + TE was demonstrated in a cell-free system [39], Additionally, in the absence of the reducing cofactor NADPH, cell-free DEBS 1+TE converted... 

By decreasing the concentration of acid sites [BEA(75) and BEA(140) series], only a slight decrease of isobutyryl chloride conversion is observed (56% and 53%, respectively). However, the higher turnover frequency (TOE) observed with BEA(140) (3.11 mim ) underscores the importance of the hydrophobicity of zeolites in the reaction between polar and nonpolar compounds. With increasing hydrophobicity of the zeolite, toluene can easily diffuse to the channel system and, also, desorption of polar isopropyltolyl-ketones is much easier. The selectivity toward thepara-isopropyltolylketone for BEA(25), BEA(75), and BEA(140) is 75%, 78%, and 80%, respectively. 

To extend this powerful new dihydrofuran synthesis to more complex systems, related reactions with branched /1-dicarbonyl systems were investigated [20]. hi a similar fashion, the cfs-fused furanoids 40 and 41 were prepared from hexane-2,4-dione (37), ethyl isobutyryl acetate (38), and 2. These targets are important chiral synthons, since there are many natural products bearing ethyl and isopropyl residues on furanoid rings. The flexibility of this method was also tested with the aromatic /3-diketone 39 yielding furanoid 42, which is an important system for tetralone synthesis (Scheme 8). 

A brief survey of pertinent aspects of comparative enzymology based on those references is presented here. The two enzyme systems which operate sequentially in fatty acid synthesis are acetyl-CoA carboxylase (ACC) and fatty acid synthetase (FAS). Straight-chain fatty acid synthesis operates using acetyl-CoA as the chain initiator, while branched-chain compounds are synthesized using isobutyryl-, isovaleryl- or 2-methylbutyryl-CoA esters. In either case malonyl-CaA acts as the unit for fatty acid chain extension and NADPH (reduced nicotinamide adenine dinucleotide phosphate) as the hydrogen donor. The repeated condensation of malonyl-CoA with the appropriate chain initiator by FAS ultimately produces the appropriate end-product, usually 16 0, palmitic acid, in the great majority of organisms (292, 293). 

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