@article{mbs:/content/journal/micro/10.1099/00221287-53-2-275, author = "Nurminen, T. and Suomalainen, H.", title = "Location and Activity of the Respiratory Enzymes of Baker's Yeast and Brewer's Bottom Yeast Grown under Anaerobic and Aerobic Conditions", journal= "Microbiology", year = "1968", volume = "53", number = "2", pages = "275-285", doi = "https://doi.org/10.1099/00221287-53-2-275", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-53-2-275", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", abstract = "SUMMARY: The activity of the electron-transport enzymes of baker's yeast or brewer's bottom yeast, grown under anaerobic conditions, was very low. When anaerobic baker's yeast was cultured aerobically to the mid-exponential phase with limited carbon source, the activity of the electron-transport enzymes increased 3- to 10-fold and, correspondingly, the activity in the stationary phase rose 10- to 50-fold. For brewer's bottom yeast the increase of activity induced by oxygen in the aerobic stationary phase was only about 3- to 4-fold and the activity was clearly lower than that of baker's yeast. The activity of the electron-transport enzymes accumulated in the 10,000 g sediment, which under aerobic conditions contained 60-80% of the total activity; the NADPH2 oxidase system formed an exception. The activity of the enzymes of the citric acid cycle also increased under aerobic conditions but only 2- to 10-fold in baker's yeast of the aerobic stationary phase; in brewer's bottom yeast the increase during oxygen adaptation was proportionally greater. The bulk of the enzymes of the citric acid cycle were found in the postmitochondrial supernatant, while the 10,000 g sediment contained 20 to 40% of the total activity. The 10,000 g sediment of anaerobically grown baker's yeast contained mitochondrial precursors, while the 10,000 g sediment from the aerobic exponential phase contained mitochondria with a more developed structure, showing a respiratory control ratio of 1.4-1.7 with several substrates. The internal structure of the mitochondria was not completely developed until the aerobic stationary phase, where the uptake of oxygen with several substrates also increased many fold.", }