Cartoon showing the movement of the iron sulfur protein of the bc1 complex, and other features of the Qo-site ballet

The Crofts Lab


Summary of Current Research Interests

Structure/function relationships in photosynthetic energy conversion; structure of membrane proteins; mechanism of energy conservation; photosynthesis in intact plants; energetic and informational fluxes of the biosphere, chronognosis, and evolutionary epistemology

Our work is based on the complementarity between biophysical, structural and molecular engineering approaches to the study of biological mechanism. Molecular engineering protocols have provided tools for modification of protein structure, but their utility is greatly increased by combining them with other approaches. Most importantly, knowledge of the structure of the target protein and the ability to assay the functional consequences of specific mutagenesis make it possible to explore the mechanism of catalysis at the molecular level.

Other interests include biophysical aspects of electron transfer and the coupling to ATP synthesis through the proton gradient, studies of the control of photosynthetic electron transfer in the coupled steady-state; the supramolecular organization of electron transfer chains; the mechanism and evolution of the cyt bc1/b6f family of complexes in plants and bacteria; the mechanism of action of inhibitors (including herbicides); and the role of  thioredoxin in activation and control of chloroplast ATP-ase and other enzymes, and the control and modulation of photosynthesis in intact plants in the laboratory and under field conditions. We have developed novel instruments that allow us to explore individual reactions of the photosynthetic apparatus in intact plants. We are using these in the lab and in the field to try to understand how photosynthesis is regulated under natural conditions, including studies of the mechanisms of down regulation in strong light, photoinhibition, and response to environmental stress.

The bc1 complex of Rhodobacter sphaeroides

The bc1complex Home Page.

Structure of the bc1-complex.

Mechanistic aspects of the Qo-site of the bc1-complex.

The modified Q-cycle.

Animations Outline of modified Q-cycle.

 Working models of the modified Q-cycle, including movies and Chime-based animation.

 3-D Movie showing the mechanism we have suggested for the Qo-site.

Relation between structure and function explored using molecular engineering. (Paper from the Xth. Internatl. Photosynthesis Congress, Montpelier, with amplified Figs.)

Marcus-Bronsted program for analysis of energy-gap law parameters in Qo-site reaction. Files available include executable program, Visual Basic source code, and Manual.

Heterogeneity in local domains determines reaction characteristics for bimolecular processes - a response to the supercomplex hypothesis.

Structural Prediction.

PSAAM package, and Walsh-Crofts Structural Propensity Indices

Function and Structure of Photosystem II.

Current interests in photosystem II.

How Plants Protect themselves against High Light.

Energetics of the biosphere, chronognosis, and evolutionary epistemology

Movie showing herbicide uptake by a leaf (MPEG)
Click here for more recent fluoresence movies from Jim Fenton, Brian Wade and Lloyd Wax.
Download Multimedia Xplorer for MPEG (and most other image and video formats) viewing. 

Protein Viewers

Chime Protein Viewer for Netscape. Click HELP link for download insructions.

Protein Data Viewer for Windows (PDVWIN Package)

E-mail to A.R. Crofts

A.R. Crofts' Home Page

Back to Welcome page

Teaching

Biological Energy Conversion Biophysics 354

This course is taught in the Fall semester by ARC, and is available on the WWW. The course contains many Chime tutorials on proteins of interest in bioenergetics and photosysnthesis.

Other useful stuff.

Chime and Rasmol Links

Rasmol is a program for viewing macromolecular structures coded in the Brookhaven Protein Data Bank (PDB) format. Chime is a plugin for Netscape (versions 3.0 and higher) which uses many of the Rasmol commands to allow viewing of PDB files (and many other formats) in the browser.
All PDB files used in Chime can be downloaded using the File option under the Chime menu. These can then be explored in greater detail using Rasmol.