caa a22 4500 465749097 CHVBK 20180323111828.0 cr unu---uuuuu 170327e19900101xx s 000 0 eng 10.1007/BF00322515 doi (NATIONALLICENCE)springer-10.1007/BF00322515 Long term stability of mitochondrial superoxide dismutase activity in NIST diets I-V [Elektronische Daten] [D. Scholfield, G. Iyengar, S. Reiser] Summary: Mitochondrial superoxide dismutase (MnSOD) is a ubiquitos, manganese containing enzyme common to most plant and animal cells. In order to determine the stability of an enzyme in frozen diet composites after long term storage, MnSOD activity was measured over a three year period in five different NIST samples. The CuZn SOD activity was below the detectable limits of the method employed. MnSOD activity was found in unhomogenized, well mixed portions of US Diets I and III. Recently, frozen aliquots of the five diet samples, which had been thawed and refrozen in April 1988, were again thawed and analyzed for SOD enzyme activity. The total enzyme activity was reduced from 50 to 60% as compared to that found in April 1988. The effect of extremes in temperature as a result of repetitive freezing and thawing is known to reduce the biological activity of other peptides. The results of this project indicate that NIST frozen diet composite samples will retain enzyme activity for as long as two years, and this may provide an additional organic substance measurable in these diet composite materials. Springer-Verlag, 1990 Scholfield D. Agricultural Research Service, B.H.N.R.C., Carbohydrate Nutrition Laboratory, USDA, 20705, Beltsville, MD, USA aut Iyengar G. National Institute of Standards and Technology, USDC, 20899, Gaithersburg, MD, USA aut Reiser S. Agricultural Research Service, B.H.N.R.C., Carbohydrate Nutrition Laboratory, USDA, 20705, Beltsville, MD, USA aut Fresenius' Journal of Analytical Chemistry Springer-Verlag 338/4(1990-01-01), 453-454 0937-0633 338:4<453 1990 338 216 https://doi.org/10.1007/BF00322515 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00322515 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Scholfield D. Agricultural Research Service, B.H.N.R.C., Carbohydrate Nutrition Laboratory, USDA, 20705, Beltsville, MD, USA aut NATIONALLICENCE 700 1- Iyengar G. National Institute of Standards and Technology, USDC, 20899, Gaithersburg, MD, USA aut NATIONALLICENCE 700 1- Reiser S. Agricultural Research Service, B.H.N.R.C., Carbohydrate Nutrition Laboratory, USDA, 20705, Beltsville, MD, USA aut NATIONALLICENCE 773 0- Fresenius' Journal of Analytical Chemistry Springer-Verlag 338/4(1990-01-01), 453-454 0937-0633 338:4<453 1990 338 216 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer