Hydroxy butyryl

One of the steps in fatty-acid biosynthesis is the dehydration of (i )-3-hydroxy-butyryl ACP to give frans-crotonyl ACP. Does the reaction remove the pro-JR or the pro-5 hydrogen from C2 ... 

E. coli C. Kluyveri 4-hydroxy-butyryl-CoA dehydrogenase and R. eutropha phaC P(4HB) 4-hydroxybutyric acid and glucose 68... 

Poly(3HB) is synthesized in bacteria from acetyl-CoA by a three-step reaction (Fig. 1). The first enzyme of the pathway, 3-ketothiolase, catalyzes the condensation of two molecules of acetyl-CoA to form acetoacetyl-CoA. Aceto-acetyl-CoA reductase subsequently reduces acetoacetyl-CoA to R-3-hydroxy-butyryl-CoA, which is then polymerized by the PHA synthase to produce poly(3HB). Since acetyl-CoA is present in plant cells in the cytosol, plastid, mitochondrion, and peroxisome, the synthesis of poly(3HB) in plants could, in... 

Methyl 3-hydroxy butyric aciduria 2-Methyl 3-hydroxy butyryl-CoA dehydrogenase... 

Methyl 3-hydroxy butyryl- BKT deficiency, MHBD deficiency... 

STEP 7 Dehydration of /3-hydroxy-butyryl ACP yields crotonyl ACP. 

Other immuno-stimulants were isolated by Umezawa and his colleagues in Tokyo from microbial sources. These substances, which strongly inhibited peptidases, could also activate T-cell immune responses in mammals. One of them, bestatin, has found clinical use in those types of cancer where immune-repression can be demonstrated. Bestatin is 3-amino-4-phenyl-2-hydroxy-butyryl-leucine, and is non-toxic to Man (Carter, Sakurai and Umezawa, 1981). 

In addition to hydrase properties, crystalline crotonase is believed to possess three different catalytic properties it acts as an isomerase that converts the cis to the trans form it catalyzes the racemization of the d( —) hydroxybutyryl CoA to the l( -h) hydroxy-butyryl CoA (racemase activity) and it catalyzes the transfer of crotonyl-S-pantetheine to CoA to yield crotonyl CoA (transcrotonylase activity). This association of several catalytic properties with a single crystalline protein suggests either that crystallization is no absolute criterion for purity or that pure protein may present several rather different catalytic properties, each of which may be elicited at different active sites. 

STEPS 6-8 OF FIGURE 23.6 REDUCTION AND DEHYDRATION The ketone carbonyl group in acetoacetyl ACP is next reduced to the alcohol j8-hydroxy-butyryl ACP by j8-keto thioester reductase and NADPH. R Stereochemistry results at the newly formed chirality center in the )8-hydroxy thioester product. (Note that the systematic name of a butyryl group is butanoyl.)... 

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