Enzymes sequence

Enzyme Sequence Around Serine (s) Sequence Around Histidine (R) ... 

Restriction enzymes, sequence-dependent cleavage of DNA by, 12 497—498 Restriction fragment linked polymorphism (RFLP), 12 500 procedure, 12 103-104 Restriction sites, as genetic markers, 12 500... 

Cell components or metabolites capable of recognizing individual and specific molecules can be used as the sensory elements in molecular sensors [11]. The sensors may be enzymes, sequences of nucleic acids (RNA or DNA), antibodies, polysaccharides, or other reporter molecules. Antibodies, specific for a microorganism used in the biotreatment, can be coupled to fluorochromes to increase sensitivity of detection. Such antibodies are useful in monitoring the fate of bacteria released into the environment for the treatment of a polluted site. Fluorescent or enzyme-linked immunoassays have been derived and can be used for a variety of contaminants, including pesticides and chlorinated polycyclic hydrocarbons. Enzymes specific for pollutants and attached to matrices detecting interactions between enzyme and pollutant are used in online biosensors of water and gas biotreatment [20,21]. 

S ATP -P acetate <1-18> (<8> acetate kinase/phosphotransacetylase, major role of this two-enzyme sequence is to provide acetyl coenzyme A which may participate in fatty acid synthesis, citrate formation and subsequent oxidation [1] <3> function in the metabolism of pyruvate or synthesis of acetyl-CoA coupling with phosphoacetyltransacetylase [15] <11> function in the initial activation of acetate for conversion to methane and CO2 [19] <10> key enzyme and responsible for dephosphorylation of acetyl phosphate with the concomitant production of acetate and ATP [30]) (Reversibility r <1-18> [1, 2, 5-21, 24-27, 29-33]) [1, 2, 5-21, 24-27, 29-33]... 

The a/ 3 barrel shown in Fig. 2-28 consists of 8 consecutive (3-a units in a symmetric array.265 266 By 1995 over 40 of these barrels had been identified in a diverse group of enzymes. One bifunctional enzyme contains two a/(3 barrels. Although the nature of the reaction catalyzed varies, the active site is always found in the center of the barrel at the C-terminal ends of the 8 parallel (3 strands and therefore between the N termini of the surrounding helices. The enzyme sequences show no homology and frequent occurrence of the 8-stranded barrel may reflect the fact that it is a natural packing arrangement of (3-a units. However, a 10-stranded barrel of this type has also been found.267... 

Much attention has focused on vitamin K 1 because of its function as an obligatory cofactor in enzymic sequences central to blood clotting. The role of molecular oxygen in the formation of vitamin K oxide 2 has been studied intensively, and the mechanism of the 1 —> 2 transformation has been the subject of much controversy. Oxidation of 1 with basic hydrogen peroxide also gives 2, and two obvious mechanisms can be postulated for this model oxidation. 180 labelling studies have been used to distinguish between these mechanisms. 

Michael Smith Univ. of British Columbia, Canada site-directed gene mutagenesis to change enzyme sequence (Nobel prize 1993)... 

This line has been initiated in the late 70s by Rechnitz group (1), who introduced enzyme sequences into enzyme electrodes. The field has been considerably widened by introducing the competitive (parallel), recycling and accumulation sensors. The following main merits of such sensors shall be pointed out ... 

The vast array of functional diversity generated in this experiment is shown in Figure 5 (see color insert). The frequency of improved clones ranged from 4% to 12% of the active library in any single parameter. In addition, the diversity of combinations of properties ranged well beyond the properties of the parental enzymes. Sequence analysis of some of the best performing clones under each set of conditions revealed that variants with similar properties could be encoded by very different sequences. Thermostability, for example, could be conferred by any one of at least three different genetic elements. In many applications, a... 

Restriction enzyme Sequence recognized Fragment end-structure after cleavage... 

Figure 4 shows the deduced amino acid sequence from the nucleotide sequence of the two clones and compares it with the complete rice seed enzyme deduced amino acid sequence (9). There is a large amount of identity between the amino acid sequences, corresponding to about 76 . Most notable is the sequence between residues 424-434 in spinach leaf where it has been shown that Lys 431 is the site of chemical modification by PLP (7,9). There is complete agreement of this sequence in the same area with the rice seed enzyme sequence 462-472. Moreover, there is complete identity of the deduced amino acid sequences of amino acids 408-434 in the spinach leaf enzyme 51 kd subunit with amino acids 446-472 of the rice endosperm enzyme subunit. 

Crystallographic studies at 2.5 A resolution have been carried out on the enzyme from E.coli [67] (Fig. 15) and Lactobacillus casei [68,69] (Fig. 16). Residue numbers in what follows refer to the L. casei enzyme sequence [70]. The binding sites for the substrate and coenzyme are not located in separate domains, but are composed of overlapping portions involving mainly the N-terminal two-thirds of the polypeptide... 

Figure 13.4 Transmembrane receptors must bind their Ligand and propagate their signal across the plasma membrane, usually by way of a protein conformational change. On the cytosolic face of the plasma membrane, that change initiates an enzymic sequence (e.g. G-protein or tyrosine kinase), leading to downstream events.

Several architectural paradigms are known for polyketide and fatty acid synthases. While the bacterial enzymes are composed of several monofunctional polypeptides which are used during each cycle of chain elongation, fatty acid and polyketide synthases in higher organisms are multifunctional proteins with an individual set of active sites dedicated to each cycle of condensation and ketoreduction. Peptide synthetases also exhibit a one-to-one correspondence between the enzyme sequence and the structure of the product. Together, these systems represent a unique mechanism for the synthesis of biopolymers in which the template and the catalyst are the same molecule. 

As in morphine biosynthesis, the knowledge of the enzyme sequences allows a more detailed understanding of the localization of the enzymes (104). Strictosidine synthase (Fig. 2b) seems to be localized to the vacuole (105), and strictosidine glu-cosidase is believed to be associated with the membrane of the endoplasmic reticulum (73, 106). Tabersonine-16-hydroxylase is associated with the endoplasmic reticulum membrane (98) N-methyl transferase activity is believed to be associated... 

Inhibitors of cathepsin K illustrate the principles developed to inhibit this class of enzyme. This enzyme sequence was detected in 1994 by sequencing of human DNA for the human genome project (126).Cathepsin K was found to be inhibited by leupeptin (63) and by compound (64), which surprisingly binds "backwards" to the active site (Fig. 15.30). A hypothesis to develop symmetrical inhibitors of cathepsin K derived from the superposition of both aldehydes on the carbonyl carbon this led to the diamino ketone TSA (65). The diamino ketone moiety seems to work in several classes of cysteine proteases (127). 

Adipic acid Alkanes Cyclohexane Mutated organisms A five-enzyme sequence... 

Triglycerides also are now commonly measured with enzyme reagents directly in plasma or serum. Reagents combining all the required enzymes, cofactors, and buffers are available from various manufacturers, and as for cholesterol, such reagents are optimized for use with particular instrument-calibrator systems. Several different enzyme sequences have been used. In all of the methods, the first step is the lipase-catalyzed hydrolysis of triglycerides to glycerol and fatty acids. 

The development of analytically useful enzyme electrodes is limited by the availability of purified and stable enzyme preparations. In an effort to extend the range of measurable species using ISE devices further, Rechnitz and co-workers (Rl) recently introduced bacterial- and tissue-based bio-selective electrode systems. These sensors are prepared in much the same manner as the enzyme probes except that whole intact cells are utilized as the immobilized reagents. There are several potential advantages to this novel approach, including (1) no need to extract and purify the enzymes involved, i. e., low cost (2) enzymes which are unstable when extracted from the cell may be used in situ to maximize and preserve their activity (3) if desired enzyme reactions require cofactors, these co ctors need not be added to the assay mixture because they are already present in the intact cell and (4) analytical reactions involving multistep enzyme sequences already present in the cells may be used to detect given analytes. 

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