T. M. Weaver

T. M. Weaver is the published author name credited on the 1995 structural study of Fumarase C from Escherichia coli. The paper lists a University of Minnesota biochemistry affiliation. Its initials are retained here as the verified scientific byline.^[ref]

The study determined the four-subunit protein complex at $2.0$ ångströms crystallographic resolution. A tungstate derivative, acting as a competitive inhibitor, helped locate an active site containing contributions from three of the four protein subunits. Thus, the site was not simply a pocket belonging to one isolated chain.^[ref]

This gives an illuminating reason to distinguish folding from assembly. A purified protein subunit could retain its own folded shape yet fail to form a complete active site if a neighboring contribution is missing. Conversely, identifying a conserved catalytic group in a sequence does not establish that the required protein complex has assembled.

An original probability model illustrates the possible amplification. Suppose an idealized site requires three independently functional subunit contributions, each present with probability $p$. Its probability of being complete is $p^3$. With $p=0.9$, this is $0.729$, rather than $0.9$. In that model, losing $10\%$ of individual contributions leaves $27.1\%$ of sites incomplete. This is not a measured activity law for Fumarase C: independent availability, random assembly and all-or-nothing site function are explicit assumptions. A real defect could affect assembly, chemical turnover or both.

The structural observation motivates complementary measurements: assess protein oligomerization separately from reaction rate, then ask whether altered assembly accounts for altered catalysis. A crystal structure supplies a concrete spatial hypothesis about these relationships, while functional measurements test its consequences.