Enzymes, degradation

The yields of DNA intake by the cells are, however, very low. The few bacteria containing the hybrid plasmid need to be sorted out. One technique applies a plasmid which encodes for antibiotic-degrading enzymes, e.g for penicillinase and tetracyclinase, and thus... 

Several enzymes, none of which are completely specific for the enkephalins, are known to cleave Leu- and Met-enkephalin at various peptide bonds. The main enzymes that degrade enkephalin are 2inc metaHopeptidases. The first enkephalin-degrading enzyme to be identified, an aminopeptidase which cleaves the amino terminal Tyr-Gly bond (179), has been shown to be aminopeptidase-N (APN) (180). It is a cytoplasmic enzyme which is uniformly distributed throughout the brain. The increased analgesic activity of synthetic enkephalins substituted by D-amino acids at position 2, eg,... 

Litde is known about metaboHc inactivation of ( -endorphin and the dynorphins. NEP, and to a lesser extent APN, are only weaMy active against P-endorphin (183). Enzymes are known which degrade P-endorphin in vitro under nonphysiological conditions (202) or which inactivate P-endorphin by N-acetjlation (203). Alack of specific degradative enzymes for these peptides may account for their relatively long half-life in vivo though this has not been definitively estabUshed. 

Of particular importance for modifications of starch are the enzyme degradation products such as glucose symps, cyclodextrins, maltodextrins, and high fmctose com symps (HFCS). Production of such hydrolysis products requites use of selected starch-degrading enzymes such as a-amylase,... 

Table 4. Starch-Degrading Enzymes of Industrial Importance...

A second family of carbohydrate-degrading enzymes, the lysozymes, produces synergistic antimetastatic activity when co-adrninistered with cisplatin [15663-27-1] to mice whose primary tumor had been surgically removed (51). 

In animals, the enzymes of fatty acid synthesis are components of one long polypeptide chain, the fatty acid synthase, whereas no similar association exists for the degradative enzymes. (Plants and bacteria employ separate enzymes to carry out the biosynthetic reactions.)... 

The ECE isoforms show different subcellular distributions and enzymatic characteristics (Table 2). ECE-la and ECE-lc are mainly expressed at the cell surface, whereas ECE-lb, ECE-Id and ECE-2 are expressed intracellularly. Plasma membrane-bound ECE cleaves big-ET-1 circulating in the blood, whereas intracellular ECE isoforms are involved in the generation of mature endothelins. In addition, ECEs (as well as NEP and the insulin-degrading enzyme) contribute to the degradation of amyloid (3 (A 3) peptide. 

While these functions can be a carried out by a single transporter isoform (e.g., the serotonin transporter, SERT) they may be split into separate processes carried out by distinct transporter subtypes, or in the case of acetylcholine, by a degrading enzyme. Termination of cholinergic neurotransmission is due to acetylcholinesterase which hydrolyses the ester bond to release choline and acetic acid. Reuptake of choline into the nerve cell is afforded by a high affinity transporter (CHT of the SLC5 gene family). 

ACE not only activates angiotensin but is also involved in the metabolism of other peptides, e.g., it is a major kinin-degrading enzyme. Therefore, ACE inhibitors also increase kinin concentrations. Furthermore, it has recently been shown that these drugs potentiate kinin effects by modulating a direct interaction between the ACE protein and the kinin B2 receptor, which is independent from the enzymatic activity of ACE. Kinin potentiation may be involved in the beneficial action of ACE inhibition since kinins are known to exert cardio- and renoprotective actions. 

The substitution pattern of arabinosyl side chains in AX from cereal flours and bran, based on the structural analysis of ohgomer fragments produced by xylan-degrading enzymes of known mode of action, was described by several authors [60-63], and various structural models were created [39,60]. fii a recent study [64] on the fine structure of wheat flour AX, a method was... 

Tsuchii, A. and Takeda, K., Rubber-degrading enzyme from a bacterial culture, Appl. Bnviron. Microbiol, 56, 269, 1990. 

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