The Carbon Monoxide-binding Pigment of Liver Microsomes¶
Why this mattered¶
Omura and Sato’s 1964 paper mattered because it turned a puzzling spectroscopic signal in liver microsomes into a definable biological entity: a carbon monoxide-binding hemoprotein with an unusual reduced CO difference spectrum peak near 450 nm. This shifted microsomal drug metabolism from being treated mainly as a diffuse enzymatic activity to being anchored in a measurable pigment, soon named cytochrome P-450. The key conceptual move was that the endoplasmic-reticulum “microsomal” fraction contained a distinct heme system capable of binding small molecules, not merely contaminating mitochondrial cytochromes or nonspecific heme proteins.
Once this pigment could be detected spectrophotometrically, researchers could quantify it, purify it, compare it across tissues and species, and connect it to oxidative metabolism of drugs, steroids, fatty acids, carcinogens, and environmental chemicals. That made possible the modern cytochrome P450 field: inducible enzyme systems, isozyme families, genetic polymorphisms in drug response, and mechanistic studies of monooxygenation. Later breakthroughs in pharmacology, toxicology, endocrinology, and chemical carcinogenesis depended on the paper’s central advance: it gave investigators a physical handle on the enzymes that explain why organisms transform foreign and endogenous compounds in highly specific, variable, and clinically consequential ways.
Abstract¶
(no abstract available)
Related¶
- cite → PROTEIN MEASUREMENT WITH THE FOLIN PHENOL REAGENT — The liver microsome pigment study uses the Lowry Folin phenol assay to quantify protein in microsomal preparations.
- enables ← PROTEIN MEASUREMENT WITH THE FOLIN PHENOL REAGENT — The Lowry Folin phenol assay enabled protein quantification needed to characterize cytochrome P-450 as the carbon monoxide-binding pigment of liver microsomes.