Biology Reference
In-Depth Information
Fig. 11.15 The fluorescence image of single molecules of cholesterol oxidase (COx) immobilized
in agarose gel. When FAD is illuminated at 442 nm (see the
upward arrow
in Fig.
11.16
), the
prosthetic group absorbs this photon and emits fluorescence at 530 nm (see the
solid downward
arrow
in Fig.
11.16
). This image was taken in 4 min with an inverted fluorescence microscope by
raster-scanning the sample with a focused laser beam of 500 nW at the excitation wavelength.
Each individual fluorescent spot indicates the presence of a single molecule of COx. The intensity
variations are due to different longitudinal positions of COx molecules in the gel (Reproduced
data on COx cannot be fully explained unless the traditional physics- and chemis-
try-based mathematical formalisms are supplemented with the evolution-derived
catalytic information
of the kind discussed by the Ranganathan group (Poole and
Ranganathan 2006; Socolich et al. 2005; S
uel et al. 2003) and others. One possible
way by which “catalytic information” may affect the probability of the occurrence
of a given waiting time (or a rate constant) was constructed using as a metaphor the
potential energy transfer between the
garage door
and its
spring
as explained in
Table
11.12
in Sect.
11.3.3
.
€
11.3.1 Waiting Time Distribution of Cholesterol Oxidase
Cholesterol oxidase is a 53,000 Da protein with 504 amino acid residues that
catalyzes the oxidation of cholesterol by oxygen to form cholesterone. The active
