Malate dehydrogenase isoenzymes catalyzing the oxidation of malate to oxaloacetate are highly active enzymes in mitochondria, in peroxisomes, in chloroplasts, and in the cytosol. Determination of the primary structure of the isoenzymes has disclosed that they are encoded in different nuclear genes. All three organelle-targeted malate dehydrogenases are synthesized with an amino terminal extensi...

The 3-ketoacyl-ACP synthase (KAS) II is a fatty-acid-related enzyme which catalyzes the elongation of 16:0-acyl carrier protein (ACP) to 18:0-ACP in plastids. The fatty acid biosynthesis 1-1 (fab1-1) mutant of Arabidopsis thaliana is partially deficient in its activity of Arabidopsis thaliana 3-ketoacyl-ACP synthase 2 (AtKAS2), and its phenotype has been intensively studied in connection with t...

Prosthetic lipoyl groups are required for the function of several essential multienzyme complexes, such as pyruvate dehydrogenase (PDH), α-ketoglutarate dehydrogenase (KGDH), and the glycine cleavage system (glycine decarboxylase [GDC]). How these proteins are lipoylated has been extensively studied in prokaryotes and yeast (Saccharomyces cerevisiae), but little is known for plants. We earlier ...

We have engineered Escherichia coli to overproduce saturated and monounsaturated aliphatic methyl ketones in the C₁₁ to C₁₅ (diesel) range; this group of methyl ketones includes 2-undecanone and 2-tridecanone, which are of importance to the flavor and fragrance industry and also have favorable cetane numbers (as we report here). We describe specific improvements that resulted in a 700-fold enha...

4-Bromocrotonic acid was found to effectively inhibit respiration supported by either palmitoylcarnitine or acetoacetate in coupled rat heart mitochondria. Partial inhibition was observed when 3-hydroxybutyrate served as a substrate, whereas pyruvate-supported r spiration was unaffected by the inhibitor. Thus, 4-bromocrotonic acid inhibits fatty acid oxidation a d ketone body degradation. W...

A cDNA coding for 3-ketoacyl-acyl-carrier protein (ACP) synthase III (KAS III) from spinach (Spinacia oleracea; So KAS III) was used to isolate two closely related KAS III clones (Ch KAS III-1 and Ch KAS III-2) from Cuphea hookeriana. Both Ch KAS IIIs are expressed constitutively in all tissues examined. An increase in the levels of 16:0 was observed in tobacco (Nicotiana tabacum, WT-SR) leaves...

Production of β-ketoacyl-CoA, which is catalyzed by 3-ketoacyl-CoA synthase (KCS), is the first step in very long chain fatty acid (VLCFA) biosynthesis. Here we identified 58 KCS genes from Gossypium hirsutum, 31 from G. arboreum and 33 from G. raimondii by searching the assembled cotton genomes. The gene family was divided into the plant-specific FAE1-type and the more general ELO-type. KCS tr...

Some plants produce methylketones as potent defense compounds against various insects. Wild tomato (Solanum habrochaites), a relative of the cultivated tomato (Solanum lycopersicum), synthesizes large amounts of 2-methylketones in its glandular trichomes, but cultivated tomato trichomes contain little or no methylketones. Two enzymes, Solanum habrochaites methylketone synthase1 (ShMKS1) and ShM...

Fatty acids (FAs) are diverse molecules, and such diversity is important for lipids to exert their functions under several environmental conditions. FA elongation occurs at the endoplasmic reticulum and produces a variety of FA species; the FA elongation cycle consists of four distinct enzyme reactions. For this cycle to be driven efficiently, there must exist coordinated regulation of protein ...

The stopped flow method has been used to determine the pH dependence of the kinetics of the binding of NADPH to chicken liver fatty acid synthase over the pH range 6.0-8.5. The kinetics is consistent with a one-step binding mechanism, and the pH dependence of the second order rate constant indicates that an ionizable group either on the enzyme or on NADPH with a pK, of 6.1 is of importance in t...