With the help of an automatic protein sequenator, we have verified a prediction made by us in a recent paper, namely that residue 16 in Candida krusei cytochrome c is a glutamine and not a glutamic acid. Neurospora crassa cytochrome c now remains the only mitochondrial cytochrome c which apparently does not have a glutamine at this position. In the course of this investigation, from two strains of Candida krusei we isolated two cytochromes which differ in amino acid composition. One of them seems to correspond to that described in the literature. Two of the differences have been located. [ABSTRACT FROM AUTHOR]