The yeast Saccharomyces cerevisiae is a facultative anaerobe and its mitochondrial morphology is linked to its metabolic activity. The Sco proteins (Sco1p and Sco2p) were characterized as proteins required for copper delivery to cytochrome c oxidase. Our results indicated a higher fermentative capacity of the sco1-Delta mutant in comparison to the control and the sco2-Delta mutant strains. The mitochondrial proteome analysis showed that the sco1-Delta mutant down-regulated components of the respiratory chain, the TCA cycle and transport of metabolites across the mitochondrial membrane. This evidence suggests that the absence of Sco1p causes irreversible damage to the mitochondria.