Premium
The dual role of oxygen in avocado fruit respiration: Kinetic analysis and computer modelling of diffusion‐affected respiratory oxygen isotherms
Author(s) -
TUCKER M. L.,
LATIES G. G.
Publication year - 1985
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1985.tb01218.x
Subject(s) - respiration , persea , oxygen , chemistry , cytochrome c oxidase , alternative oxidase , oxidase test , respiration rate , horticulture , botany , biochemistry , biology , enzyme , organic chemistry
. Oxygen plays a dual role in affecting the rate of respiration of avocado fruit ( Persea americana Mill, cv. Hass). The respiration rate v. oxygen concentration curve for steady state avocado fruit respiration is biphasic. The curve becomes monophasic, however, when measured under conditions of rapidly changing oxygen concentration in a closed circulating system. The results are interpreted as indicating that oxygen at relatively high concentrations modulates respiration independent of its interaction with the terminal oxidase—presumably cytochrome oxidase. A computer model is presented which takes into account the effect of diffusion barriers on the kinetics of oxygen utilization as a function of concentration in avocado fruit. The model is used to make predictions concerning the apparent K m of the terminal oxidase or oxidases in avocado fruit. It is concluded that the apparent K m of the terminal oxidase of uninhibited avocado fruit is that of cytochrome oxidase, and that the alternative, cyanide‐resistant oxidase of avocado fruit does not contribute appreciably to the uninhibited respiration of preclimacteric or climacteric avocado fruit.