Enzyme, biosynthesis

Dutton, R.J. Bitton, G. Koopman, B. Enzyme biosynthesis versus enzyme activity as a basis for microbial toxicity testing. Toxic. Assess. 1988, 3, 245 -253. 

As noted earlier, the velocity of any enzyme-catalyzed reaction is dependent upon the amount of effective enzyme present. Enzyme biosynthesis, like that of all proteins, is under genetic control, a long-term process. Biosynthesis of enzymes may be increased or decreased at the genome level. Various hormones can activate or repress the mechanisms controlling gene expression. Enzyme levels are the result of the balance between synthesis and degradation. This enzyme turnover may be altered by diverse physiological conditions, by hormone effects, and by the level of metabolites. 

Mueller OT, Honey NK, Little LE Mucolipidosis II and III. The genetic relationships between two disorders of lysosomal enzyme biosynthesis./ Clin Invest 72 1016-1023,1983. 

Figure 10.45 Modular PKS enzymes biosynthesis of 6-deoxy erythronolide B (10.70) and modified biosynthetic products 10.71 10.73.

Falkenhagen, H. and Stockigt, J. (1995) Enzymic biosynthesis of vomilenine, a key intermediate of the ajmaline pathway, catalysed by a novel cytochrome P450-dependent enzyme from plant cell cultures of Ramuolfa serpentina. Z. Naturforsch., 50c, 45-53. 

The first part of this review will be devoted to enzyme biosynthesis by pancreas and the second part to chemical characterization of certain pancreatic enzymes. Some of these enzymes have already been comprehensively discussed in recent volumes of this series (6, 7). 

Another interesting problem is the study of the enzymatic content of the pancreas, not only as a function of time after stimulation, but also as a function of various external factors such as the composition of the diet and the nutritional state of the animals. Several laboratories have already attempted to establish the existence of an adjustment of enzyme biosynthesis to the main component of the diet and to find out the mechanism by which the digestive process may influence enzyme biosynthesis (58-60). 

Natural cyclic amides such as 5,6-dihydrouracil, uracil and 5,6-dihydrothymine as well as hydantoin, 5-methylhydantoin and 5-hydroxymethylhydantoin are effective inducers for enzyme biosynthesis (for a more detailed review on induction experiments see reference13 ). In some cases, the dihydropyrimidinase (D-hydantoinase) is associated with an N-carbamoyl-D-amino acid amidohydrolase (D-carbamoylase) and a hydantoin racemase1301. The previously proposed identity of the D-N-carbamoylase with the p-ureidopropionase (E. C. 3.5.1.6), which was assumed to be responsible for the hydrolysis of N-carbamoyl-P-alanine (see Fig. 12.4-7) 131-351 is no longer valid since the investigations of Ogawa et al. on different aerobic bacteria showed that the... 

Synthesis of other polysaccharides involves many of the same mechanisms as for glycogen, particularly the use of nucleotide-linked sugars as activated biosynthetic intermediates and glycosyltransferase enzymes. Biosynthesis of several polysaccharides is described briefly below ... 

Nykiforuk, C.L., T.L. Furukawa-Stoffer, P.W. Huff, et al. 2002. Characterization of cDNAs encoding diacyglycerol acyltransferase from cultures of Brassica napus and sucrose-mediated induction of enzyme biosynthesis. Biochim. Biophys. Acta 1580 95-109. 

IX. Involvement of Adenosine Cyclic 3, S -Phosphate in Enzyme Biosynthesis. 224... 

D. J. Hook, R.P. Elander, R.B. Morin, Recent developments with cell free extracts on the enzymic biosynthesis of penicillins and cephalosporins in Peptide-antibiotics . Biosynthesis and Function, H. Kleinkauf, H. von Dohren eds. de Gruyter, Berlin 1982, pp 84-100... 

The importance of understanding the regulation of NAD synthesis could not escape the reader. One can postulate various mechanisms of regulation (1) the existence of anabolic enzyme inhibitors (2) the adjustment of a delicate balance between anabolic and catabolic enzyme activities and (3) a regulation of the enzyme biosynthesis by repression of the gene responsible for their elaboration. 

Studies on bacterial mutation have shown that the induction of a specific enzyme is usually accompanied by an increase in activity of several other enzymes involved in the same catabolic or anabolic pathways. When E. coli are grown in the presence of galactosides, the formation of j8-galactosidase is induced, and it has been established that the new enzyme formed (1000 times the activity present in the wild type of E. coli) is not derived from the activation of preexisting proenzyme, but from the net synthesis of new enzyme. In 1953, Monod [213] discovered that the activity of tryptophan synthetase is inhibited by tryptophan and certain of its analogs. It was established that the inhibition or repression resulted from a block of the enzyme biosynthesis. 

In addition to the classical galactosemia, there is a form of transferase deficiency that seems to result from alteration of the regulation (see Fig. 3-18) of the enzyme biosynthesis. Thus, in this form of galactosemia (referred to as the Duarte form), the homozygous have 50% and the heterozygous 75% of the normal levels of transferase activity [65]. Another form of galactosuria has been described in a few cases with normal transferase and epimerase activity but low galactokinase [66, 67]. 

G.Weber, R.L.Singhal, N.B.Stamm and S.K.Srivastava, Hormonal Induction and Suppression of Liver Enzyme Biosynthesis, Fedn Proc. Fedn Am. Socs exp. Biol. 24, 745-754 (1965). 

Examples of antagonistic interaction include the effects of ABA and auxin on root tip surface charge (Tanada 1972) the effects of ABA and kinetin on coleoptile elongation (Khan and Downing 1968), the effects of GA and tannins on enzyme biosynthesis (Jacobson and Corcoran 1977) and the effects of ethylene and either GA3 or cytokinin on fruit senescence (Goldschmidt et al. 1977). 

The jS-D-glucosidase of Mucor racemosus was shown to be biosynthesized when the organism was grown in the presence of such diverse carbon sources as glycerol, lactate, o-xylose, o-ribose, methyl and phenyl a-o-glucopyrano-sides, maltose, and cellobiose. Enzyme biosynthesis was strongly repressed in the presence of hexoses and of adenosine 3, 5 -monophosphate. The role of adenosine 3, 5 -monophosphate in the control of jS-D-glucosidase synthesis in M. racemosus was discussed. 

Smith (1962) has drawn an analogy between memory and substrate induction in microorganisms. He pointed out a number of common features in these two events. Particularly, a nerve impulse induces an increase in the activity of some enzyme systems (e.g., esterases). This is caused by the stimulation of secretion and synthesis. The mediators of these increases can serve as specific inductors which initiate the increase ojf enzyme biosynthesis. Such induction and the associated success of training can depend upon the amount of substrate. 

Enzymes Biosynthesis in Medinm with Coconnt Oil by Solid State Fermentation... 

Coconut oil cake is a waste by-product obtained after the oil extraction fium dried coconut. The major compounds fium the coconut oil cake are short chain saturated fatty acids, which were proposed to be used as a carbon substrate somce in solid-state fermentation (SSF) for enzymes biosynthesis. This approach in which the coconut oil cake represents a cheap way for the bioproducts synthesis is a new one and was adopted in the last years. The first report on enzymes synthesis using coconut oil cake was published by Ramachandran and coworkers, in 2004. The researchers optimized the production of a-amylase using a fungal culture of Aspergillus oryzae strain in SSF cultivation system on a medium based on raw coconut oil cake and it was obtained an a-amylase activity of 1372 U/g dw, in 24 h. Eight... 

Despite the orderly process of enzyme biosynthesis and the denaturation and degradation of older enzymes, there are problems of stability of proteins in solution. There is continual endogenous generation of peroxides, ammonia, hydrogen ions, carbon monoxide, superoxide, singlet oxygen, and hydroxyl radicals. Oxygen, as well as cations, anions, and trace metals are present in all cellular fluids. These various substances may inhibit or destabilize various enzymes. 

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