scholarly journals The incorporation of tritiated retinyl moiety into the active-site lysine residue of bacteriorhodopsin

1979 ◽  
Vol 183 (1) ◽  
pp. 175-178 ◽  
Author(s):  
E Mullen ◽  
M G Gore ◽  
M Akhtar
Keyword(s):  
Active Site ◽  
Lysine Residue ◽  
Halobacterium Halobium ◽  
Amino Group ◽  
Purple Membranes

Purple membranes were isolated from Halobacterium halobium bleached and regenerated with all-trans-[15-3H]retinal. The incorporation of label was 1.2 mol of retinal/mol of bacterio-opsin. The [3H]retinyl-bacterio-opsin obtained from regeneration was hydrolysed to give tritiated retinyl-lysine, which, on hydrogenation to N-epsilon-perhydro[3H]retinyl-lysine and reaction with 1-fluoro-2,4-dinitrobenzene, gave bis-(2,4-dinitrophenyl)-N-epsilon-perhydro[3H]retinyl-lysine. This result confirmed that the retinyl moiety of the chromophore is attached to an epsilon-amino group of lysine.

The Reaction of Aminoacylase with Chloromethylketone Analogs of Amino Acids

1977 ◽  
Vol 32 (9-10) ◽  
pp. 769-776 ◽  
Author(s):  
Jürgen Frey ◽  
Werner Kordel ◽  
Friedhelm Schneider
Keyword(s):  
Amino Acids ◽  
Aspartic Acid ◽  
Active Site ◽  
Lysine Residue ◽  
Amino Group ◽  
Sh Groups ◽  
Competitive Inhibitors ◽  
Kinetics Of ◽  
Covalently Bound

Abstract1. Aminoacylase is irreversibly inactivated by the chloromethylketone analogs of benzyloxy-carbonyl-L-alanine, L-alanine, L-leucine, L-aspartic acid (β), tosyl-L-phenylalanine and L-leucyl-L-alanine. The kinetics of the inactivation of the enzyme by the halo-methylketones were investigated.2. Leucyl-and alanyl chloromethylketone inactivate the enzyme by blocking of 4 SH groups. Experiments with [U-14C] leucyl chloromethylketone confirm that maximal 4 residues are covalently bound to the protein.3. Inactivation of the enzyme by benzyloxycarbonylalanyl and tosylphenylalanyl chloromethyl­ ketone is the result of the substitution of the £-amino group of one lysine residue per active site and not of SH groups. However, in the presence of competitive inhibitors these halomethylketones react only with the SH groups of the enzyme, too.

scholarly journals Bacterial pseudokinase catalyzes protein polyglutamylation to inhibit the SidE-family ubiquitin ligases

Science ◽  
2019 ◽  
Vol 364 (6442) ◽  
pp. 787-792 ◽  
Author(s):  
Miles H. Black ◽  
Adam Osinski ◽  
Marcin Gradowski ◽  
Kelly A. Servage ◽  
Krzysztof Pawłowski ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Host Cell ◽  
Crystal Structures ◽  
Active Site ◽  
Bond Formation ◽  
Ubiquitin Ligases ◽  
Carboxyl Group ◽  
Amino Group ◽  
Isopeptide Bond

Enzymes with a protein kinase fold transfer phosphate from adenosine 5′-triphosphate (ATP) to substrates in a process known as phosphorylation. Here, we show that the Legionella meta-effector SidJ adopts a protein kinase fold, yet unexpectedly catalyzes protein polyglutamylation. SidJ is activated by host-cell calmodulin to polyglutamylate the SidE family of ubiquitin (Ub) ligases. Crystal structures of the SidJ-calmodulin complex reveal a protein kinase fold that catalyzes ATP-dependent isopeptide bond formation between the amino group of free glutamate and the γ-carboxyl group of an active-site glutamate in SidE. We show that SidJ polyglutamylation of SidE, and the consequent inactivation of Ub ligase activity, is required for successful Legionella replication in a viable eukaryotic host cell.

scholarly journals Acrolein, an irreversible active-site-directed inhibitor of deoxyribose 5-phosphate aldolase?

1976 ◽  
Vol 153 (2) ◽  
pp. 495-497 ◽  
Author(s):  
D C Wilton
Keyword(s):  
Schiff Base ◽  
Rate Constant ◽  
Active Site ◽  
Order Rate Constant ◽  
Lysine Residue ◽  
Prolonged Incubation ◽  
Enzyme Active Site ◽  
First Order ◽  
Substrate Analogue ◽  
Pseudo First Order

The enzyme deoxyribose 5-phosphate aldolase was irreversibly inactivated by the substrate analogue acrolein with a pseudo-first-order rate constant of 0.324 min-1 and a Ki (apparent) of 2.7 × 10(-4) m. No inactivation was observed after prolonged incubation with the epoxide analogues glycidol phosphate and glycidaldehyde. It is suggested that the acrolein is first activated by forming a Schiff base with the enzyme active-site lysine residue and it is the activated inhibitor that reacts with a suitable-active-site nucleophile.

Amino-terminal groups in zymogen activation: effect of nitrous acid on pepsin

1969 ◽  
Vol 47 (12) ◽  
pp. 1099-1101 ◽  
Author(s):  
T. Hofmann
Keyword(s):  
Nitrous Acid ◽  
Lysine Residue ◽  
Amino Group ◽  
Serine Proteinases ◽  
Zymogen Activation ◽  
Activation Effect ◽  
Amino Terminal ◽  
Tryptophan Residues ◽  
Terminal Amino ◽  
Isoleucine Residue

Nitrous acid rapidly deaminates the N-terminal isoleucine residue of pepsin. The enzyme retains more than 60% of its activity. The loss of 30–40% activity can be ascribed to the reaction of two tryptophan residues with nitrous acid. The single lysine residue is also deaminated. These results are in contrast to those obtained with serine proteinases where nitrous acid causes inactivation due to the deamination of the N-terminal amino group.

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