Premium
Oxidation of Glucose, Ribose, Alanine, and Glutamate by Leishmania braziliensis panamensis 1
Author(s) -
KEEGAN FRANK P.,
SANSONE LISA,
BLUM J. J.
Publication year - 1987
Publication title -
the journal of protozoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 0022-3921
DOI - 10.1111/j.1550-7408.1987.tb03156.x
Subject(s) - pentose phosphate pathway , ribose , alanine , biochemistry , incubation , biology , metabolism , chemistry , glycolysis , amino acid , enzyme
The metabolism of [1‐ 14 C]‐ and [6‐ 14 C]glucose, [1‐ 14 ]ribose, [1‐ 14 C]‐ and [U‐ 14 C]alanine, and [1‐ 14 C]‐ and [5‐ 14 C]glutamate by the promastigotes of Leishmania braziliensis panamensis was investigated in cells resuspended in Hanks' balanced salt solution supplemented with ribose, alanine, or glutamate. The ratio of 14 CO 2 produced from [1‐ 14 C]glucose to that from [6‐ 14 C]glucose ranged from about two to six, indicating appreciable carbon flow through the pentose phosphate pathway. A functional pentose phosphate pathway was further demonstrated by the production of 14 CO 2 from [1‐ 14 C]ribose although the rate of ribose oxidation was much lower than the rate of glucose oxidation. The rate of 14 CO 2 production from [1‐ 14 C]glucose was almost linear with time of incubation, whereas that of [6‐ 14 C]glucose accelerated, consistent with an increasing rate of flux through the Embden‐Meyerhof pathway during incubation. Increasing the assay temperature from 26°C to 34°C had no appreciable effect on the rates or time courses of oxidation of either [1‐ 14 C]‐ or [6‐ 14 C]glucose or of [1‐ 14 C]ribose. Both alanine and glutamate were oxidized by L. b. panamensis , and at rates comparable to or appreciably greater than the rate of oxidation of glucose. The ratios of 14 CO 2 produced from [1‐ 14 C]‐ to [U‐ 14 C]alanine and from [1‐ 14 C]‐ to [5 ‐14 C]glutamate indicated that these compounds were metabolized via a functioning tricarboxylic acid cycle and that most of the label that entered the tricarboxylic acid cycle was oxidized to carbon dioxide. Heating the cultures for 6 or 12 h at 34°C, which converts the promastigotes into an ellipsoidally shaped intermediate form, decreased the rates of oxidation of glucose, alanine, and glutamate. The oxidation of glutamate decreased by about 50% and 70% after a 6‐h or 12‐h heat treatment, respectively. Returning the heated cultures to 26°C initiated a reversion to the promastigote form and recovery of the rate of glucose oxidation, but glutamate oxidation did not return to control levels by 19 h at 26°C.