Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0085593 (chills)
 4,268 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Oxygen consumption by alternative oxidase (AOX), present in mitochondria of many angiosperms, is known to be cyanide-resistant in contrast to cytochrome oxidase. Its activity in potato tuber (Solanum tuberosum L.) was induced following chilling treatment at 4 degrees C. About half of the total O(2) consumption of succinate oxidation in such mitochondria was found to be sensitive to SHAM, a known inhibitor of AOX activity. Addition of catalase to the reaction mixture of AOX during the reaction decreased the rate of SHAM-sensitive oxygen consumption by nearly half, and addition at the end of the reaction released nearly half of the consumed oxygen by AOX, both typical of catalase action on H(2)O(2). These findings with catalase suggest that the product of reduction of AOX is H(2)O(2) and not H(2)O, as previously surmised. In potatoes subjected to chill stress (4 degrees C) for periods of 3, 5 and 8 days the activity of AOX in mitochondria increased progressively with a corresponding increase in the AOX protein detected by immunoblot of the protein.
 ...
PMID:Evidence for H(2)O(2) as the product of reduction of oxygen by alternative oxidase in mitochondria from potato tubers. 2005 Dec 23

The mosaic MSC16 cucumber (Cucumis sativus L.) mutant, which houses a rearranged mitochondrial genome, has altered respiratory chain activity, with a dysfunctional Complex I, increased external NADH dehydrogenases (ND(ex)) activity, and a higher alternative oxidase (AOX) capacity and AOX protein level. In the present study, changes in oxidative defense metabolism resulting from the respiratory chain dysfunction in the MSC16 mutant were compared with those induced by chilling. Chilling increased the enzymatic and non-enzymatic antioxidant defense systems in the wild-type (WT) but not in MSC16, which displays elevated antioxidant defenses as a result of the mitochondrial mutation. The high AOX capacity and protein level in MSC16 were unchanged as a result of chilling, whereas chilling increased these parameters in WT leaves. In mitochondria isolated from WT plants, superoxide was produced to a similar extent in the matrix and the intermembrane space, but in MSC16 mitochondria superoxide was produced largely within the intermembrane space. Mitochondria isolated from both genotypes after chilling showed increased superoxide production within the intermembrane space. Cytochemical detection revealed an increased abundance of H2O2 in the mitochondrial membrane in mesophyll cells of MSC16 leaves. The mitochondrial mutation also resulted in changes in the antioxidative defense system, including AOX, which were similar to those observed following chilling. The results presented here support the hypothesis that AOX is an effective marker of the cellular reprogramming resulting from stress. Moreover, we propose a role for reactive oxygen species (ROS) generated within the mitochondria in signal transduction.
 ...
PMID:Chilling stress and mitochondrial genome rearrangement in the MSC16 cucumber mutant affect the alternative oxidase and antioxidant defense system to a similar extent. 1954 67

Chill treatment of potato tubers for 8 days induced mitochondrial O2 consumption by cyanide-insensitive alternative oxidase (AOX). About half of the total O2 consumption in such mitochondria was found to be sensitive to salicylhydroxamate (SHAM), a known inhibitor of AOX activity. Addition of catalase to the reaction mixture of AOX during the reaction decreased the rate of SHAM-sensitive O2 consumption by nearly half, and addition at the end of the reaction released half of the O2 consumed by AOX, both typical of catalase action on H2O2. This reaffirmed that the product of reduction of O2 by plant AOX was H2O2 as found earlier and not H2O as reported in some recent reviews.
 ...
PMID:Reinstate hydrogen peroxide as the product of alternative oxidase of plant mitochondria. 2128 May 68