Motility of Triose Phosphate Isomerase: Hydrogen-Exchange Studies performed by a Novel Dialysis Technique

1973 ◽  
Vol 1 (5) ◽  
pp. 1155-1158
Author(s):  
C. A. BROWNE ◽  
S. G. WALEY
1974 ◽  
Vol 141 (3) ◽  
pp. 753-760 ◽  
Author(s):  
Christopher A. Browne ◽  
Stephen G. Waley

The3H–H exchange of chicken muscle and rabbit muscle triose phosphate isomerases was studied. Their behaviour was mostly very similar. ‘Exchange-in’ (acquisition of radioactivity when protein was incubated in3H2O) was measured at 37°C and at pH7.5, and the rates of exchange of the native and liganded enzymes were compared. Inhibitors and substrates retarded exchange, substrates showing the most marked effect; structural rearrangements in the enzyme may thus play some part in catalysis. The inhibitor phosphoglycollate affected the rabbit enzyme, but had little or no effect on the chicken enzyme. ‘Exchange-out’ (loss of radioactivity from protein previously labelled by incubation in3H2O) was measured by hollow-fibre dialysis. When ligand was removed during the course of dialysis (by replacing buffer that contained ligand with buffer that lacked ligand) there was a prompt decrease in the number of labelled H atoms of the protein. Analysis of the curves provides some information about the number and half-lives of the responsive H atoms. Ligands decrease the motility of the protein and affect about one-fifth of the chain. Low concentrations of glycerol 3-phosphate have an effect that is greater than expected.


2021 ◽  
pp. 247255522110181
Author(s):  
Andreas Vogt ◽  
Samantha L. Eicher ◽  
Tracey D. Myers ◽  
Stacy L. Hrizo ◽  
Laura L. Vollmer ◽  
...  

Triose phosphate isomerase deficiency (TPI Df) is an untreatable, childhood-onset glycolytic enzymopathy. Patients typically present with frequent infections, anemia, and muscle weakness that quickly progresses with severe neuromusclar dysfunction requiring aided mobility and often respiratory support. Life expectancy after diagnosis is typically ~5 years. There are several described pathogenic mutations that encode functional proteins; however, these proteins, which include the protein resulting from the “common” TPIE105D mutation, are unstable due to active degradation by protein quality control (PQC) pathways. Previous work has shown that elevating mutant TPI levels by genetic or pharmacological intervention can ameliorate symptoms of TPI Df in fruit flies. To identify compounds that increase levels of mutant TPI, we have developed a human embryonic kidney (HEK) stable knock-in model expressing the common TPI Df protein fused with green fluorescent protein (HEK TPIE105D-GFP). To directly address the need for lead TPI Df therapeutics, these cells were developed into an optical drug discovery platform that was implemented for high-throughput screening (HTS) and validated in 3-day variability tests, meeting HTS standards. We initially used this assay to screen the 446-member National Institutes of Health (NIH) Clinical Collection and validated two of the hits in dose–response, by limited structure–activity relationship studies with a small number of analogs, and in an orthogonal, non-optical assay in patient fibroblasts. The data form the basis for a large-scale phenotypic screening effort to discover compounds that stabilize TPI as treatments for this devastating childhood disease.


1972 ◽  
Vol 247 (10) ◽  
pp. 3361-3362
Author(s):  
Stuart W. Hawkinson ◽  
Chin Hsuan Wei ◽  
Fred C. Hartman ◽  
I. Lucille Norton ◽  
J. Ralph Einstein

The Lancet ◽  
1989 ◽  
Vol 334 (8667) ◽  
pp. 871 ◽  
Author(s):  
B. Dallapiccola ◽  
G. Novelli

Triose phosphate isomerase is a dimeric enzyme of molecular mass 56000 which catalyses the interconversion of dihydroxyacetone phosphate (DHAP) and D-glyceraldehyde-3-phosphate. The crystal structure of the enzyme from chicken muscle has been determined at a resolution of 2.5 A, and an independent determination of the structure of the yeast enzyme has just been completed at 3 A resolution. The conformation of the polypeptide chain is essentially identical in the two structures, and consists of an inner cylinder of eight strands of parallel |3-pleated sheet, with mostly helical segments connecting each strand. The active site is a pocket containing glutamic acid 165, which is believed to act as a base in the reaction. Crystallographic studies of the binding of DHAP to both the chicken and the yeast enzymes reveal a common mode of binding and suggest a mechanism for catalysis involving polarization of the substrate carbonyl group.


1986 ◽  
Vol 22 (2) ◽  
pp. 135-137
Author(s):  
ARTHUR C. L. CLARK ◽  
MARGARET A. SZOBOLOTZKY

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