= T. M. Weaver
{c}
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.<The multisubunit active site of fumarase C from Escherichia coli by T. M. Weaver and others>[Published byline, affiliation and Abstract; Nature Structural Biology 2, 654–662]{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.<The multisubunit active site of fumarase C from Escherichia coli by T. M. Weaver and others>[Abstract: tungstate derivative and multisubunit active site]{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.
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