(Catalytic mechanism of hydrogenase from aerobic N2-fixing microorganisms). [Azotobacter vinelandii:a1]

Technical Report · Tue Jan 01 00:00:00 EST 1991

OSTI ID:5452120

The results of this DOE-sponsored project have contributed to our understanding of the catalytic mechanism of A. vinelandii hydrogenase. A group of inhibitors have been characterized. These provide information about the different types of redox clusters involved in catalysis and the roles of each. One group has already used acetylene in a study of three desulfovibrian hydrogenases and shown that onbly the NiFe hydrogenases are inhibited. The inhibitor studies are also being extended to other enzymes. We have characterized a number of special properties of A. vinelandii hydrogenase. While the NiFe dimeric hydrogenases are now recognized as a large group of similar enzymes, there are differences in the spectral and catalytic properties which are not explained by their similar redox inventories, identical subunit structures, immunological cross reactivity and conserved sequences. Surprisingly, we only see a significant EPR signal attributable to Ni after the enzyme has been inactivated with O{sub 2} and then re-reduced (though not reactivated). Acetylene, which does not substantially perterb the EPR signal of active hydrogenase, does result in a new absorption envelope in the UV-Vis spectrum. Overall, the results of this project have revealed the complex interactions of the redox clusters in catalysis through studies of inhibitor mechanisms and spectral properties. 14 refs., 9 figs.

• Research Organization: Oregon State Univ., Corvallis, OR (United States)
• Sponsoring Organization: USDOE; USDOE, Washington, DC (United States)
• DOE Contract Number: FG06-90ER20013
• OSTI ID: 5452120
• Report Number(s): DOE/ER/20013-1; ON: DE91017001
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
AZOTOBACTER
HYDROGENASES
ENZYME INHIBITORS
BIOCHEMICAL REACTION KINETICS
ENZYME ACTIVITY
ACETYLENE
AMINO ACID SEQUENCE
ANTIBODIES
CYANIDES
ELECTRON SPIN RESONANCE
IRON
METALLOPROTEINS
MICROORGANISMS
NICKEL
NITRIC OXIDE
OLIGONUCLEOTIDES
OXIDATION
PROGRESS REPORT
REDOX REACTIONS
REDUCTION
ULTRAVIOLET SPECTRA
ALKYNES
BACTERIA
CHALCOGENIDES
CHEMICAL REACTIONS
DOCUMENT TYPES
ELEMENTS
ENZYMES
HYDROCARBONS
KINETICS
MAGNETIC RESONANCE
METALS
MOLECULAR STRUCTURE
NITROGEN COMPOUNDS
NITROGEN OXIDES
NUCLEIC ACIDS
ORGANIC COMPOUNDS
OXIDES
OXIDOREDUCTASES
OXYGEN COMPOUNDS
PROTEINS
REACTION KINETICS
RESONANCE
SPECTRA
TRANSITION ELEMENTS
550200* - Biochemistry
550700 - Microbiology
550500 - Metabolism