T-State and R-State of Hemoglobin скачать в хорошем качестве

T-State and R-State of Hemoglobin

For hemoglobin to function as an oxygen-carrier in the blood, it must have an equilibrium between the two main states of its quaternary structure, the unliganded "deoxy" or "T state" versus the liganded "oxy" or "R state". The unliganded (deoxy) form is called the "T" (for "tense") state because it contains extra stabilizing interactions between the subunits, specifically ionic interactions. In the high oxygen affinity R-state conformation, these ionic interactions are lost, and the tetramer is described as "relaxed". In some organisms this difference is so pronounced that their Hb molecules dissociate into dimers in the oxygenated form. Structural changes that occur during this transition can illuminate how such changes result in important functional properties, such as cooperativity of oxygen binding and allosteric control by pH and anions. Problem: What effect does high concentrations of carbon dioxide have on hemoglobin? A) It marks the hemoglobin for degradation B) It stimulates the red blood cell to make more hemoglobin C) It induces the hemoglobin to adopt the R-structure D) It induces the hemoglobin to adopt the T-structure * E) It has no effect