PubMed · 5423953
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
R M Munkley, J Stuart. 1970. Rapid cyanmethaemoglobin estimation.. https://doi.org/10.1136/jcp.23.2.190
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Rapid reduction of cyano-met hemoglobin (Hb+CN-) leads to the formation of an intermediate species, the cyanide derivative of ferrous hemoglobin, which dissociates to unliganded hemoglobin because of the extremely low affinity of the ligand for the ferrous heme iron. The properties of the intermediate were studied by transient spectroscopy in human hemoglobin and its isolated alpha and beta chains, in the presence and absence of CO. When mixing with dithionite, the time courses of reduction of the heme iron and dissociation of cyanide overlap considerably; addition to the reaction mixture of the redox indicator methyl viologen considerably increases the rate of reduction and allows unequivocal determination of the spectroscopic and kinetic properties of the intermediate. The results show that (i) the dissociation of cyanide from the isolated alpha and beta chains (as well as the (alpha CO)2(beta + CN-)2 hybrid) is a simple process; (ii) the two chains display similar rate parameters, but show spectroscopic inequivalence, both in the Soret and the visible regions; (iii) cooperative effects are shown to control the rate of dissociation of cyanide from hemoglobin, similarly to what happens for oxygen; and (iv) allosteric effectors (typically inositol hexaphosphate) increase the overall rate of dissociation by stabilization of the T state. We have, therefore, shown for the first time that the dissociation of cyanide from ferrous hemoglobin is controlled by the quaternary state, thereby adding one more ligand to the analysis of the structure-function relationships in hemoglobin.
Cellular proteins were not synthesized by germinating ascospores of Neurospora tetrasperma until 90 min after spore activation. Nevertheless, immediately after activation these ascospores developed a cyanide-sensitive respiration which increased throughout this 90-min period. At 90 min the respiratory rates accelerated rapidly, protein synthesis was initiated, and transcripts for a subunit of the mitochondrial ATPase, employed here as a representative mRNA, began to accumulate.
Explore the source record for details and available documents.