Enzymes, synthesis with

The Increase In AP activity is stimulated by bile acids. A rise in bile acids, which is considered to be the most sensitive and earliest marker of cholestasis, precedes any elevation in AP. The latter derives from enzyme synthesis with increased secretion into the blood. Under pathological conditions, bile duct AP is formed, which is a sensitive marker for hepatobiliary diseases, cholestasis and space-occupying lesions of the liver. The sensitivity is 80-100% in cholestatic diseases. AP activity is usually higher in obstructive jaundice and cholangitis than in intrahepatic obstructions, and it is highest in the vanishing bile duct disease or in complete obstruction. (13, 39, 41) (s. tabs. 5.9 13.2-13.4)... 

Induced cells contain a mechanism for concentrating inducers within the cells, and this mechanism appears to play a part in the induction process. The formation of enzyme depends on the continued presence of inducer. The rate of enzyme synthesis with adequate amoimts of inducer is proportional to the growth of the bacteria. When the inducer is removed (by suspending the centrifuged bacteria in fresh medium), enzyme synthesis stops abruptly. The enzyme already formed, however, is stable, and persists unchanged for many generations. Sulfur-labeled amino acids have been used to demonstrate that the induced enzyme is formed directly from free amino acids, and that proteins already in the bacteria do not contribute amino acids to the new enzyme. In the absence of the inducer, the adaptive enzyme retains its label. Some properties of inducers were found in a study of penicillinase production by BadUus cereusJ With this system it was shown that in a brief exposure a small amount of penicillin is specifically bound within the cells, and is not hydrolyzed, but stimulates the production of several equivalents of penicillinase. 

Neuropeptide Y. Neuropeptide Y [82785 5-3] (NPY) (255) is a 36-amiao acid peptide that is a member of a peptide family including peptide YY (PYY) [81858-94-8, 106338-42-5] (256) and pancreatic polypeptide (PPY) [59763-91-6] (257). In the periphery, NPY is present in most sympathetic nerve fibers, particulady around blood vessels and also in noradrenergic perivascular and selected parasympathetic nerves (66). Neurons containing NPY-like immunoreactivity ate abundant in the central nervous system, particulady in limbic stmctures. Coexistence with somatostatin and NADPH-diaphorase, an enzyme associated with NO synthesis, is common in the cortex and striatum. 

Some related antibacteiials are also included with the sulfonamides. The azo dye, Piontosil (3) is metabolized to sulfanilamide in and was the piogenitoi of the sulfa dmgs. Also, the antibacteiial sulfones, eg, dapsone (4), are believed to act in a similai fashion on enzymes involved with synthesis of fohc acid, leading to bacterial growth inhibition. 

Microorganisms exhibit nutritional preferences. The enzymes for common substrates such as glucose are usually constitutive, as are the enzymes for common or essential metabohc pathways. Furthermore, the synthesis of enzymes for attack on less common substrates such as lactose is repressed by the presence of appreciable amounts of common substrates or metabolites. This is logical for cells to consei ve their resources for enzyme synthesis as long as their usual substrates are readily available. If presented with mixed substrates, those that are in the main metabolic pathways are consumed first, while the other substrates are consumed later after the common substrates are depleted. This results in diauxic behavior. A diauxic growth cui ve exhibits an intermediate growth plateau while the enzymes needed for the uncommon substrates are synthesized (see Fig. 24-2). There may also be preferences for the less common substrates such that a mixture shows a sequence of each being exhausted before the start of metabolism of the next. 

A second form of inhibition could occur whereby the product AA acts to inhibit the synthesis of the enzyme associated with the committed step in... 

The nucleus contains a large number of proteins other than histones. These so-called nonhistone proteins may or may not be tightly associated with the chromosomes. For example, the nucleus contains enzymes associated with the synthesis of RNA and DNA these are nonhistone proteins, but they are not part of the structure of chromosomes. One group of nonhistone proteins are the high mobility group (HMG) proteins, named for their rapid movement on polyacryl-amide gel electrophoresis. The HMG proteins, but not histone HI, are associated with the chromatin that is most active in RNA synthesis. 

One of the recent fundamental advances in carbohydrate chemistry has been enzymic synthesis in vtiro this has now been realized with dextran8 and with levan.8 However, since phosphate sugars are not involved in the enzymic syntheses of these two bacterial polysaccharides, it is obvious that phosphorylation is just one process for the natural synthesis of polysaccharides. 

Each reaction of p oxidation is catalyzed by a different enzyme. Chemically, they re pretty much the same as the reverse of the individual reaction of fatty acid synthesis, with two exceptions (1) p oxidation uses FAD for the formation of the double bond at the C-2 position, and (2) the reactions occur with the fatty acid attached to CoA rather than to the pantetheine of a multienzyme complex. 

Synthesis of sucrose 6 -phosphate by an enzymic method using uridine 5 -(a-D-glucopyranosyl diphosphate) plus D-glucose 6-phosphate has been reported.126-131 The first, unambiguous, chemical synthesis of sucrose 6 -phosphate was achieved by Buchanan and coworkers.18 The reaction of 2,3,4,6,l, 3, 4 -hepta-0-acetylsucrose, prepared by five steps of synthesis, with cyanoethyl phosphate in pyridine gave a crude product from which sucrose 6 -phosphate was isolated as the barium salt. 

Enzymes associated with myelin. Several decades ago it was generally believed that myelin was an inert membrane that did not carry out any biochemical functions. More recently, however, a large number of enzymes have been discovered in myelin [37]. These findings imply that myelin is metabolically active in synthesis, processing and metabolic turnover of some of its own components. Additionally, it may play an active role in ion transport with respect not only to maintenance of its own structure but also to participation in ion buffering near the axon. 

Soil microbes. Effects include reduced microbial biomass and/or species diversity, thus affecting microbial processes such as enzyme synthesis and activity, litter decomposition, associated with carbon and nitrogen mineralization, and soil respiration ... 

Organic Synthesis with Oxidative Enzymes by Holland, H.L., VCH, Weinheim, 1992. 

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