Lysine residues dehydrogenases

Figure 2. Mechanism of PDH. The three different subunits of the PDH complex in the mitochondrial matrix (E, pyruvate decarboxylase E2, dihydrolipoamide acyltrans-ferase Ej, dihydrolipoamide dehydrogenase) catalyze the oxidative decarboxylation of pyruvate to acetyl-CoA and CO2. E, decarboxylates pyruvate and transfers the acetyl-group to lipoamide. Lipoamide is linked to the group of a lysine residue to E2 to form a flexible chain which rotates between the active sites of E, E2, and E3. E2 then transfers the acetyl-group from lipoamide to CoASH leaving the lipoamide in the reduced form. This in turn is oxidized by E3, which is an NAD-dependent (low potential) flavoprotein, completing the catalytic cycle. PDH activity is controlled in two ways by product inhibition by NADH and acetyl-CoA formed from pyruvate (or by P-oxidation), and by inactivation by phosphorylation of Ej by a specific ATP-de-pendent protein kinase associated with the complex, or activation by dephosphorylation by a specific phosphoprotein phosphatase. The phosphatase is activated by increases in the concentration of Ca in the matrix. The combination of insulin with its cell surface receptor activates PDH by activating the phosphatase by an unknown mechanism.

Figure 17-5. Oxidative decarboxylation of pyruvate by the pyruvate dehydrogenase complex. Lipoic acid is joined by an amide link to a lysine residue of the transacetylase component of the enzyme complex. It forms a long flexible arm, allowing the lipoic acid prosthetic group to rotate sequentially between the active sites of each of the enzymes of the complex. (NAD nicotinamide adenine dinucleotide FAD, flavin adenine dinucleotide TDP, thiamin diphosphate.)...

Structure of a helix F interface of human 11 (3-hydroxysteroid dehydrogenase types 1 and 2. The a helix F part of the dimer interface on 1 ip-HSD-1 and -2 is shown along with side chains of the highly conserved tyrosine and lysine residues and other residues that are oriented into the cavity that binds substrate and nucleotide cofactor. 

The fate of intracellular retinol is dependent on cell type. In the eye, trans-retinol can be esterified by LRAT or isomerized to ll-a>-ret-inol by a cell-specific isomerase (22). 11-cis-retinol is then oxidized to 11-cis-retinal by 11-cis-retinol dehydrogenase (22). 11-cis-retinal binds to opsin by forming a Schiff base with an opsin lysine residue and the resulting complex is known as rhodopsin (22). Rhodopsin is a member of the seven transmembrane family of proteins that serves as receptor for photons... 

Gordillo, E., and Machado, A., 1991, Implication of lysin residues in the loss of 6-phosphogluconate dehydrogenase activity in aging human erythrocytes, Mech. Aging Dev. 59 291-297. 

In contrast to this sensitive and highly selective response of pyruvate kinase to affinity labeling of a small number of lysine residues, lactate dehydrogenase loses activity exactly in proportion to the fraction of total lysines in the molecule converted to homoarginine with the nonspecific reagent 0-methylisourea. As would also be expected of an affinity labeling process, the rate of reaction of DMPA with the specific lysines in the catalytic sites of pyruvate kinase is very fast compared with the rate of reaction for a nonaffinity process, the former being of the order of 2500 times faster than the latter. ... 

Dallocchio, F. Matteuzzi, M. BeUini, T. Evidence for the proximity of a cysteine and a lysine residue in the active site of 6-phosphogluconate dehydrogenase... 

Amino acids important in cofactor and catalysis in human 1 lb-hydroxysteroid dehydrogenase types 1 and 2. (a) 1 lb-HSD type 1. Preference of 1 lb-HSD type 1 for NADPH resides in lysine-44 and arginine-66, which have positively charged side chains that stabilize the binding of the 2 -phosphate on NADPH. These residues also counteract the repulsive interaction between glutamic acid 69 and the phosphate group,... 

Figure 6a shows the modeled oc helix F interface in human 17 3-hydroxysteroid dehydrogenase type 1 in which phenylalanine-160 and alanine-161 form an anchor. Both residues have important stabilizing interactions across the dimer interface. Alanine-161 is 4.1 A from alanine-161 on the other subunit. Alanine-161 has a hydrophobic interaction with alanine-157, which is in the segment between the conserved tyrosine-155 and lysine-159. There is a hydrophobic... 

---