Catalytic Roles of Active-Site Amino Acid Residues of Coenzyme B12-Dependent Diol Dehydratase:  Protonation State of Histidine and Pull Effect of Glutamate

2004 ◽  
Vol 126 (49) ◽  
pp. 16207-16216 ◽  
Author(s):  
Takashi Kamachi ◽  
Tetsuo Toraya ◽  
Kazunari Yoshizawa
Keyword(s):  
Amino Acid ◽  
Active Site ◽  
Coenzyme B12 ◽  
Amino Acid Residues ◽  
Protonation State ◽  
Diol Dehydratase

scholarly journals Redox Properties of Human Medium-Chain Acyl-CoA Dehydrogenase, Modulation by Charged Active-Site Amino Acid Residues†

Biochemistry ◽  
1998 ◽  
Vol 37 (41) ◽  
pp. 14605-14612 ◽  
Author(s):  
Gina J. Mancini-Samuelson ◽  
Volker Kieweg ◽  
Kim Marie Sabaj ◽  
Sandro Ghisla ◽  
Marian T. Stankovich
Keyword(s):  
Amino Acid ◽  
Active Site ◽  
Redox Properties ◽  
Amino Acid Residues ◽  
Medium Chain ◽  
Chain Acyl

scholarly journals How [FeFe]-Hydrogenase Facilitates Bidirectional Proton Transfer

2019 ◽  
Author(s):  
Moritz Senger ◽  
Viktor Eichmann ◽  
Konstantin Laun ◽  
Jifu Duan ◽  
Florian Wittkamp ◽  
...  
Keyword(s):  
Amino Acid ◽  
Proton Transfer ◽  
Active Site ◽  
Molecular Hydrogen ◽  
H2 Production ◽  
Amino Acid Residues ◽  
Difference Spectroscopy ◽  
Dynamic Changes ◽  
In Situ Ir

Hydrogenases are metalloenzymes that catalyse the interconversion of protons and molecular hydrogen, H2. [FeFe]-hydrogenases show particularly high rates of hydrogen turnover and have inspired numerous compounds for biomimetic H2 production. Two decades of research on the active site cofactor of [FeFe]-hydrogenases have put forward multiple models of the catalytic proceedings. In comparison, understanding of the catalytic proton transfer is poor. We were able to identify the amino acid residues forming a proton transfer pathway between active site cofactor and bulk solvent; however, the exact mechanism of catalytic proton transfer remained inconclusive. Here, we employ in situ IR difference spectroscopy on the [FeFe]-hydrogenase from Chlamydomonas reinhardtii evaluating dynamic changes in the hydrogen-bonding network upon catalytic proton transfer. Our analysis allows for a direct, molecular unique assignment to individual amino acid residues. We found that transient protonation changes of arginine and glutamic acid residues facilitate bidirectional proton transfer in [FeFe]-hydrogenases.<br>

Roles of Active-Site Amino Acid Residues in Specific Recognition of DNA Lesions by Human 8-Oxoguanine-DNA Glycosylase (OGG1)

2019 ◽  
Vol 123 (23) ◽  
pp. 4878-4887 ◽  
Author(s):  
Timofey E. Tyugashev ◽  
Yury N. Vorobjev ◽  
Alexandra A. Kuznetsova ◽  
Maria V. Lukina ◽  
Nikita A. Kuznetsov ◽  
...  
Keyword(s):  
Amino Acid ◽  
Active Site ◽  
Dna Lesions ◽  
Dna Glycosylase ◽  
Amino Acid Residues ◽  
Specific Recognition

scholarly journals Role of methionine in the active site of α-galactosidase from Trichoderma reesei

1995 ◽  
Vol 308 (3) ◽  
pp. 955-964 ◽  
Author(s):  
A M Kachurin ◽  
A M Golubev ◽  
M M Geisow ◽  
O S Veselkina ◽  
L S Isaeva-Ivanova ◽  
...  
Keyword(s):  
Amino Acid ◽  
Trichoderma Reesei ◽  
Active Site ◽  
Fold Increase ◽  
Thiol Group ◽  
Competitive Inhibitor ◽  
Amino Acid Residues ◽  
Activity Curve ◽  
Oxidative Activation ◽  
Alpha Galactosidase

alpha-Galactosidase from Trichoderma reesei when treated with H2O2 shows a 12-fold increase in activity towards p-nitrophenyl alpha-D-galactopyranoside. A similar effect is produced by the treatment of alpha-galactosidase with other non-specific oxidants: NaIO4, KMnO4 and K4S4O8. In addition to the increase in activity, the Michaelis constant rises from 0.2 to 1.4 mM, the temperature coefficient decreases by a factor of 1.5 and the pH-activity curve falls off sharply with increasing pH. Galactose (a competitive inhibitor of alpha-galactosidase; Ki 0.09 mM for the native enzyme at pH 4.4) effectively inhibits oxidative activation of the enzyme, because the observed activity changes are related to oxidation of the catalytically important methionine in the active site. NMR measurements and amino acid analysis show that oxidation to methionine sulphoxide of one of five methionines is sufficient to activate alpha-galactosidase. Binding of galactose prevents this. Oxidative activation does not lead to conversion of other H2O2-sensitive amino acid residues, such as histidine, tyrosine, tryptophan and cysteine. The catalytically important cysteine thiol group is quantitatively titrated after protein oxidative activation. Further oxidation of methionines (up to four of five residues) can be achieved by increasing the oxidation time and/or by prior denaturation of the protein. Obviously, a methionine located in the active site of alpha-galactosidase is more accessible. The oxidative-activation phenomenon can be explained by a conformational change in the active site as a result of conversion of non-polar methionine into polar methionine sulphoxide.

Studies on determination of active site amino acid residues in glyoxylate synthetase from potato tuber chloroplasts

1999 ◽  
Vol 37 (2) ◽  
pp. 121-129 ◽  
Author(s):  
Machhindra T. Janave ◽  
N.Krishnan Ramaswamy ◽  
P.Madhusudanan Nair
Keyword(s):  
Amino Acid ◽  
Potato Tuber ◽  
Active Site ◽  
Amino Acid Residues
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