Enzymes utilizing

Sarcoplasmic calcium ATPase this enzyme utilizes the energy gained from hydrolysis of ATP to pump calcium from the cytosol into the stores of the sarcoplasmic reticulum. Its activity is negatively regulated by the closely associated protein phospholamban, and this inhibition is relieved upon phosphorylation of phospholamban by protein kinase A (PKA). 

Catalysis by enzymes that proceeds via a unique reaction mechanism typically occurs when the transition state intermediate forms a covalent bond with the enzyme (covalent catalysis). The catalytic mechanism of the serine protease chymotrypsin (Figure 7-7) illustrates how an enzyme utilizes covalent catalysis to provide a unique reaction pathway. 

With these results, we named the new enzyme as phenylacetaldoxime dehydratase (EC 4.99.1.7). It was also suggested that the enzyme utilizes FMN as an electron acceptor, because the value was increased about five times under anaerobic condition and the sulfite ion could replace FMN, although the enzyme requires oxidized form of FMN. It was revealed that the enzyme is a quite unique enzyme whose apparent function is to catalyze a dehydration reaction. The reaction mechanism is of much interest. 

Concerning function integration, for example, micro-flow membrane reactors can exhibit similar process intensification, as shown already for their large-scale counterparts [75]. Separation columns for proteomics, immobilizing enzymes, utilize the large surface-to-volume ratios. Surface tension differences can guide and transport liquids selectively. 

Yahiro AT, Lee SM, Kimble DO. 1964. Bioelectrochemistry. I. Enzyme utilizing bio-fuel cell studies. Biochim Biophys Acta 88 375-383. 

The differences in the rate constant for the water reaction and the catalyzed reactions reside in the mole fraction of substrate present as near attack conformers (NACs).171 These results and knowledge of the importance of transition-state stabilization in other cases support a proposal that enzymes utilize both NAC and transition-state stabilization in the mix required for the most efficient catalysis. Using a combined QM/MM Monte Carlo/free-energy perturbation (MC/FEP) method, 82%, 57%, and 1% of chorismate conformers were found to be NAC structures (NACs) in water, methanol, and the gas phase, respectively.172 The fact that the reaction occurred faster in water than in methanol was attributed to greater stabilization of the TS in water by specific interactions with first-shell solvent molecules. The Claisen rearrangements of chorismate in water and at the active site of E. coli chorismate mutase have been compared.173 It follows that the efficiency of formation of NAC (7.8 kcal/mol) at the active site provides approximately 90% of the kinetic advantage of the enzymatic reaction as compared with the water reaction. 

Yamada, E., u. W. Jacoby Enzymic utilization of Acetylenic Compounds. 

Finlay, T.H., Troll, V., Levy, M., Johnson, A.J., and Hodgins, L.T. (1978) New methods for the preparation of biospecific adsorbents and immobilized enzymes utilizing trichloro-s-triazine. Anal. Biochem. 87, 77-90. 

While the uncatalyzed reaction requires extremely high temperatures and proceeds nonspecifically, the enzymatic reaction proceeds regiospecifically and stereospecifically under physiological conditions of temperature and pressure. The P450 enzyme utilizes its iron-porphyrin centers as metal-containing... 

The key enzymes in DNA rephcation are the DNA polymerases. These enzymes utilize single-stranded DNA as template and catalyze the formation of a complementary strand. Each new nucleotide to be added is selected on the basis of its abihty to form a Watson-Crick base pair with the base on the template strand. 

Serine itself would be insufficiently nucleophilic to attack the ester carbonyl, so the reaction is facilitated by participation of the imidazole ring of histidine. The basic nitrogen in this residue is oriented so that it can remove a proton from the serine hydroxyl, increasing nucleophilicity and allowing attack on the ester carbonyl. This leads to formation of the transient acetylated enzyme, and release of choline. Hydrolysis of the acetylated enzyme utilizes water as nucleophile, but again involves the imidazole ring, and regenerates the free enzyme. 

An additional enzyme that transfers C3 rather than C2 units is called transaldolase, but, in common with aldolase (see Box 10.5), this enzyme utilizes... 

Hydroxycyclopropanecarboxylic acid phosphate HCP 34 is an analogue of phosphoenolpyruvate (PEP) 35 which is metabolized by various enzymes. HCP 34 is a potent competitive inhibitor of enzymes utilizing PEP 35, such as PEP carboxylase, enolase, pyruvate kinase, and probably other enzymes. It is a substantially better inhibitor than phospholactate 36 or phosphoglycolate 37, presumably because of the similarity of its geometric and electronic structures with phosphoenol pyruvate,Eq. 12 [28]. 

This enzyme [EC 1.4.99.1] catalyzes the oxidation-reduction reaction of a D-amino acid with an acceptor and water to generate an a-keto acid, ammonia, and the reduced acceptor. The enzyme utilizes FAD as a cofactor. Most D-amino acids, with the noted exceptions of D-aspartate and D-glutamate, can be used as substrates. K. Tsukada (1971) Meth. Enzymol. 17B, 623. 

Arylsulfatase [EC 3.1.6.1 ], also known simply as sulfatase, catalyzes the hydrolysis of a phenol sulfate, thereby producing a phenol and sulfate. This enzyme classification represents a collection of enzymes with rather similar specificities. (1) Steryl-sulfatase [EC3.1.6.2],also referred to as arylsulfatase C and steroid sulfatase, catalyzes the hydrolysis of 3-j8-hydroxyandrost-5-en-17-one 3-sulfate to 3-j8-hydroxyandrost-5-en-17-one and sulfate. The enzyme utilizes other steryl sulfates as substrates. (2) Cere-broside-sulfatase [EC 3.1.6.8], or arylsulfatase A, catalyzes the hydrolysis of a cerebroside 3-sulfate to yield a cerebroside and sulfate. The enzyme will also hydrolyze the galactose 3-sulfate bond present in a number of lipids. In addition, the enzyme will also hydrolyze ascorbate 2-sulfate and other phenol sulfates. 

This enzyme [EC 1.10.3.3], also called ascorbase, catalyzes the reaction of two ascorbate molecules with dioxygen to produce two dehydroascorbate molecules and two water molecules. The enzyme utilizes a copper ion as a cofactor. 

This enzyme [EC 2.3.1.137] catalyzes the reversible reaction of octanoyl-CoA with carnitine to yield coenzyme A and O-octanoylcarnitine. The enzyme utilizes a range of acyl-CoA derivatives as substrates, with optimal activity reported with Ce or Cs acyl groups. 

Enzymes utilizing four substrates in a single reaction. An example is carbamoyl phosphate synthetase which... 

The means of achieving stereoselectivity due to steric hindrance toward the attack of a reagent or cosubstrate. The less hindered face will be the more susceptible side. Many enzymes utilize this method of product control. 

Any process by which there is direct transfer of noncova-lently bound substrate(s) or coenzyme from the active site of the enzyme producing the metabolite to the active site of an enzyme catalyzing a succeeding step in a metabolic pathway or to another enzyme utilizing the coenzyme product. 

Synthetic studies for sialic acid and its modifications have extensively used the catabolic enzyme N-acetylneuraminic acid aldolase (NeuA E.C. 4.1.3.3), which catalyzes the reversible addition of pyruvate (70) to N-acetyl-D-mannosamine (ManNAc, 11) to form the parent sialic acid N-acetylneuraminic acid (NeuSNAc, 12 Scheme 2.2.5.23) [1, 2, 45]. In contrast, the N-acetylneuraminic acid synthase (NeuS E.C. 4.1.3.19) has practically been ignored, although it holds considerable synthetic potential in that the enzyme utilizes phosphoenolpyruvate (PEP, 71) as a preformed enol nucleophile from which release of inorganic phosphate during... 

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