An additional multifunctional proteincatalyzes steps 10 and

In the third mechanism, GTP is required inthe conversion of IMP to AMP ( step 1 ), whereas ATP is required for conversionof IMP to GMP (step 4 ), a reciprocal arrangement that tends to balance thesynthesis of the two ribonucleotides.

Aspartate is also used as the source of an amino group in thepurine pathways, in two steps.

Kerkvliet NI, Steppan LB, Smith BB, Youngberg JA, Henderson MC, & Buhler DR (1990) Role of the Ah locus in suppression of cytotoxic T lymphocyte (CTL) activity by halogenated aromatic hydrocarbons (PCBs and TCDD): Structure-activity relationships and effects in C57Bl/6 mice.


ATP is cleaved to AMP andPPi in the final step.

The detailed pathway of purine biosynthesis wasworked out primarily by Buchanan and G.

For purines, especially, non-hepatic tissues relyheavily on preformed bases - those salvaged from their own intracellularturnover supplemented by bases synthesized in the liver and delivered totissues via the blood.


The committed step in pyrimidine biosynthesis (Stryer …

This can be done by classical methods (Reynolds & Thomson, 1973) that involve the following steps: Serial dilutions of homogenates of the organs, prepared in mortars with sterile sea sand, are plated onto sheep blood agar plates; after a 24-h incubation at 37°C, the colonies are counted to determine the number of viable bacteria in the organ.

Methotrexate inhibits the first committed step of …

A three-step immunoperoxidase procedure is most suitable: the first step includes the monoclonal antibody specific for the determinants to be studied (see above), the second step, rabbit anti-mouse immunoglobulin, and the third step, swine anti-rabbit immunoglobulin, the latter two antibodies conjugated to horseradish peroxidase.

102811 Purine & Pyrimidine Biosynthesis; Shared Flashcard Set

pneumoniaefor challenge is slightly more complicated than the procedures used for Listeria; however, the potential of the model for detecting immunotoxic compounds makes the additional steps worthwhile.

102811 Purine & Pyrimidine Biosynthesis

It is a neutral lipophilic cyclic peptide consisting of 11 amino acids (relative molecular mass, 1203 Da) isolated from the fungus Tolypocladium inflatum.

(ATCase) in the first committed step of pyrimidine biosynthesis.

Their specificity to cells of the immune system may be related to the distinct pathways in purine and pyrimidine metabolism that are preferentially used by lymphocytes, such as guanine nucleotide synthesis promoted by inosine monophosphate dehydrogenase in the case of Mizoribine and RS61443.