Studies on Low Temperature Spectra of Respiratory Pigments

I. Measurement of Absorption Spectra between Liquid Helium and Room Temperatures

Abstract

A method was described for the measurement of absorption spectra of hemoproteins between liquid helium and room temperature. The split-beam spectrophotometer by Yang and Legallais was modified as follows: A halogen lamp, a double monochromator, a vibration mirror (60 c/s) of a very small amplitude and a photo-chopper system were used. A twin cuv ette composed of sample and reference compartments, was placed in the inner Dewar of double Dewar system. The outer Dewar contained liquid nitrogen and the inner one contained liquid helium.
A conductive metal plate composing lower part of the cuvette was put into the liquid helium. Two compartments of the twin cuvette were so small and close each other, that they were practically in the same optical and thermal conditions. The temperature of sample was measured by two means, a thermocouple for higher temperature (above 70°K) and a carbon resister for lower temperature. Using controlable heating system, absorption spectra of the sample could be measured at any temperature between 4.2°K and 300°K. As typical examples, the absorption spectra of cytochrome b₅ and ferrimyoglobin hydroxide were measured at various temperatures.