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Isolation, characterization, and amino acid sequences of auracyanins, blue copper proteins from the green photosynthetic bacterium Chloroflexus aurantiacusThree small blue copper proteins designated auracyanin A, auracyanin B-1, and auracyanin B-2 have been isolated from the thermophilic green gliding photosynthetic bacterium Chloroflexus aurantiacus. All three auracyanins are peripheral membrane proteins. Auracyanin A was described previously (Trost, J. T., McManus, J. D., Freeman, J. C., Ramakrishna, B. L., and Blankenship, R. E. (1988) Biochemistry 27, 7858-7863) and is not glycosylated. The two B forms are glycoproteins and have almost identical properties to each other, but are distinct from the A form. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis apparent monomer molecular masses are 14 (A), 18 (B-2), and 22 (B-1) kDa. The amino acid sequences of the B forms are presented. All three proteins have similar absorbance, circular dichroism, and resonance Raman spectra, but the electron spin resonance signals are quite different. Laser flash photolysis kinetic analysis of the reactions of the three forms of auracyanin with lumiflavin and flavin mononucleotide semiquinones indicates that the site of electron transfer is negatively charged and has an accessibility similar to that found in other blue copper proteins. Copper analysis indicates that all three proteins contain 1 mol of copper per mol of protein. All three auracyanins exhibit a midpoint redox potential of +240 mV. Light-induced absorbance changes and electron spin resonance signals suggest that auracyanin A may play a role in photosynthetic electron transfer. Kinetic data indicate that all three proteins can donate electrons to cytochrome c-554, the electron donor to the photosynthetic reaction center.
Document ID
20050000729
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
McManus, J. D.
(Arizona State University Tempe 85287-1604)
Brune, D. C.
Han, J.
Sanders-Loehr, J.
Meyer, T. E.
Cusanovich, M. A.
Tollin, G.
Blankenship, R. E.
Date Acquired
August 22, 2013
Publication Date
April 5, 1992
Publication Information
Publication: The Journal of biological chemistry
Volume: 267
Issue: 10
ISSN: 0021-9258
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: GM18865
CONTRACT_GRANT: DK15057
CONTRACT_GRANT: GM21277
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Exobiology
Non-NASA Center

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