Reporter group at the active site of acetoacetate decarboxylase. II. Ionization constant of the amino group

1971 ◽  
Vol 93 (26) ◽  
pp. 7270-7274 ◽  
Author(s):  
Fritz C. Kokesh ◽  
F. H. Westheimer
Keyword(s):  
Active Site ◽  
Ionization Constant ◽  
Amino Group ◽  
Acetoacetate Decarboxylase ◽  
Reporter Group

pK of the lysine amino group at the active site of acetoacetate decarboxylase

Biochemistry ◽  
1971 ◽  
Vol 10 (7) ◽  
pp. 1249-1253 ◽  
Author(s):  
Frank H. Westheimer ◽  
Donald E. Schmidt
Keyword(s):  
Active Site ◽  
Amino Group ◽  
Acetoacetate Decarboxylase

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.

Nitrogen and Sulfur Transferases

2007 ◽  
Author(s):  
Perry A. Frey ◽  
Adrian D. Hegeman
Keyword(s):  
Steady State ◽  
Reaction Mechanism ◽  
Active Site ◽  
Reaction Mechanisms ◽  
Radical Reaction ◽  
Amino Group ◽  
Steady State Kinetics ◽  
Ping Pong ◽  
Polar Reaction

Unlike other group transfer reactions in biochemistry, the actions of nitrogen transferring enzymes do not follow a single unifying chemical principle. Nitrogen-transferring enzymes catalyze aminotransfer, amidotransfer, and amidinotransfer. An aminotransferase catalyzes the transfer of the NH2 group from a primary amine to a ketone or aldehyde. An amidotransferase catalyzes the transfer of the anide-NH2 group from glutamine to another group. These reactions proceed by polar reaction mechanisms. Aminomutases catalyze 1,2-intramolecular aminotransfer, in which an amino group is inserted into an adjacent C—H bond. The action of lysine 2,3-aminomutase, described in chapter 7, is an example of an aminomutase that functions by a radical reaction mechanism. Tyrosine 2,3-aminomutase also catalyzes the 2,3-amino migration, but it does so by a polar reaction mechanism. In this chapter, we consider NH2-transferring enzymes that function by polar reaction mechanisms. Transaminases or aminotransferases are the most extensively studied pyridoxal-5'-phosphate (PLP)–dependent enzymes, and many aminotransferases catalyze essential steps in catabolic and anabolic metabolism. In the classic transaminase reaction, aspartate aminotransferase (AAT) catalyzes the fully reversible reaction of L-aspartate with α-ketoglutarate according to fig. 13-1 to form oxaloacetate and L-glutamate. Like all aminotransferases, AAT is PLP dependent, and PLP functions in its classic role of providing a reactive carbonyl group to function in facilitating the cleavage of the α-H of aspartate and the departure of the α-amino group of aspartate for transfer to α-ketoglutarate (Snell, 1962). PLP in the holoenzyme functions in essence to stabilize the α-carbanions of L-aspartate or L-glutamate, the major biological role of PLP discussed in chapter 3. The functional groups of the enzyme catalyze steps in the mechanism, such as the 1,3-prototropic shift of the α-proton to C4' of pyridoxamine 5'-phosphate (PMP). The steady-state kinetics corresponds to the ping pong bi bi mechanism shown at the bottom of fig. 13-1. This mechanism allows L-aspartate to react with the internal aldimine, E=PLP in fig. 13-1, to produce an equivalent of oxaloacetate, with conversion of PLP to PMP at the active site (E.PMP), the free, covalently modified enzyme in the ping pong mechanism.

scholarly journals A convenient synthesis of labelled rhodopsin and studies on its active site

1970 ◽  
Vol 119 (3) ◽  
pp. 359-366 ◽  
Author(s):  
M. D. Hirtenstein ◽  
M. Akhtar
Keyword(s):  
Conformational Change ◽  
Sodium Borohydride ◽  
Active Site ◽  
Cetyltrimethylammonium Bromide ◽  
Chemical Reactivity ◽  
Amino Group ◽  
Polar Environment ◽  
Convenient Synthesis ◽  
First Time ◽  
Native Site

Digitonin solutions of labelled rhodopsin, containing 3H in the retinyl moiety, were prepared by two related methods. Labelled rhodopsin was also prepared for the first time in cetyltrimethylammonium bromide and purified by column chromatography. It was shown that only certain rhodopsin preparations on denaturation in the dark and the reduction with sodium borohydride gave up to 60% of the radioactivity in a fraction characterized as N-retinylphosphatidylethanolamine. Such preparations also gave a lipid-linked retinyl moiety at the metarhodopsin-I stage, but, as expected, a protein-linked retinyl moiety at the metarhodopsin-II stage. Other preparations however, gave exclusively protein-bound radioactivity at the native-rhodopsin, metarhodopsin-I and metarhodopsin-II stages. It is therefore conceivable that the formation of N-retinylphosphatidylethanolamine is due to a non-enzymic reaction resulting from the transfer of the retinyl moiety from its native site to an amino group of a favourably oriented phospholipid molecule. The only firmly established aspect of the rhodopsin active site remains the demonstration in our previous work that at the metarhodopsin-II stage the retinyl moiety is linked to an ∈-amino group of lysine. On the basis of chemical reactivity it is argued that the light-induced conversion of rhodopsin into metarhodopsin II involves a profound conformational change resulting in the dislocation of the retinylideneiminium chromophore from a non-polar environment in rhodopsin to a polar environment in metarhodopsin II.

Reaction of the active site of papain with a reporter group labeled phenacyl halide

1970 ◽  
Vol 92 (23) ◽  
pp. 6980-6982 ◽  
Author(s):  
Emil T. Kaiser ◽  
Richard W. Furlanetto
Keyword(s):  
Active Site ◽  
Reporter Group
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