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The Structure Determination of M. denitrificans Cytochrome C₅₅₀


Timkovich, Russell (1975) The Structure Determination of M. denitrificans Cytochrome C₅₅₀. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/xmcg-d794.


The protein sequence and the three-dimensional folding structure for cytochrome c550 from Micrococcus denitrificans are reported. The tertiary structure resulted from an x-ray crystallographic determination. Standard protein chemistry techniques were applied to sequence all the fragment peptides from a tryptic digest of c550. This information was combined with a 2.45 Å electron density map of the protein where identifying the tryptic fragments in the map led to the correct ordering of the peptides and the final complete sequence.

The crystallization of c550 is described. Three chemical derivatives of the protein were found, PtCl42-; UO22+, and Pt(CN)42-, and these aided in the isomorphous replacement solution to the crystallographic phase problem. The interpretation and refinement of the derivatives to produce an accurate protein map is discussed.

This bacterial c550 possesses a structure similar to the known cytochromes from eukaryotic sources and from a photosynthetic bacterium. The three are contrasted to conclude that for the cytochrome family, there exists a core structure of polypeptide folding. Current proposed mechanisms for the action of c-type cytochromes are rejected as being incompatible with the c550 structure. The view is advocated that the exposed heme edge in cytochrome may be the sole active site for the molecule.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Chemistry
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Dickerson, Richard E.
Thesis Committee:
  • Unknown, Unknown
Defense Date:6 September 1974
Record Number:CaltechTHESIS:10202022-180817376
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:15044
Deposited By: Benjamin Perez
Deposited On:20 Oct 2022 19:04
Last Modified:21 Oct 2022 21:53

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