Electronic properties of protein‐methylglyoxal complexes: Strong evidence for energy‐band conduction

Various measurements, including piezoelectric, hydration isotherm, microwave Hall effect, steady‐state conduction, and dielectric properties over the effective frequency range 10 −5 to 10 10 Hz, are reported for several protein samples that have been complexed with methylglyoxal. The extent of the binding of methylglyoxal has been established using C 14 labeled methylglyoxal and scintillation counting measurements. Compared with the normal proteins, the brown complexed proteins exhibit a marked increase in electronic conductivity, free‐electron spin density, and piezoelectric response. Unlike the untreated proteins, the protein complexes also exhibit a distinct low‐frequency dielectric dispersion and at 10 GHz there is a reversal of the usual electric‐field saturation of polarizability. Compared with normal casein, the casein complex exhibits an increase in the monolayer hydration capacity. These effects can be taken as evidence that when methylglyoxal is incorporated into the structure of a protein molecule, a charge‐transfer interaction occurs resulting in the creation of mobile electron “holes.” This, in turn, satisfies the basic prerequisite for the applicability of Szent‐Györgyi's electronic theory of the “living state” and of cancer.