Studies on Yeast Hemoglobin

Among the Candida species, C. mycoderma and C. roubsta possess significant amounts of a hemoglobin‐like pigment. This pigment is identified as yeast hemoglobin by its spectroscopic properties and its ability of reversible binding with oxygen. The oxygen affinity of yeast hemoglobin in the respiring and nonrespiring cells is 0.02 μM which is identical to the value observed with an isolated yeast hemoglobin. Yeast hemoglobin in the cell can be decomposed specifically by pretreatment of the cells with ethyl hydrogen peroxide. Comparison of the hemoglobin‐free cells with the intact cells indicates that a lack of yeast hemoglobin does not cause any significant delay of cell multiplication. Neither the rate of cell respiration nor the behaviors of the redox states of mirochondrial cytochromes responding to the changes of oxygen concentration between 1 and 0.01 μM is affected by the presence or absence of yeast hemoglobin.