Role of dimerization in the control of the functioning of the human haemoglobin mutant haemoglobin Howick (beta 37 Trp-->Gly).

نویسنده

  • T Brittain
چکیده

Haemoglobin Howick shows a high oxygen affinity (p50 = 1 mmHg) and a low co-operativity (n = 1.3). Equilibrium studies show the protein to be essentially totally dimeric in the oxygenated form. A wide range of rapid kinetic experiments indicate that the deoxygenated form of the protein exists in a tetramer<-->dimer equilibrium with an associated equilibrium constant of 3 microM. These kinetic data also indicate that the oxygenated form of the protein exists in a tetramer<-->dimer equilibrium with an associated equilibrium constant of 35 mM, and furthermore clearly identifies a large increase in the rate of the tetramer-to-dimer dissociation process as the origin of the vastly increased dissociation equilibrium constants. Simulations of the protein-concentration-dependence of the oxygen-binding properties of haemoglobin Howick, based on the measured equilibrium parameters, closely fits the experimental data. The change in dimerization constant for the deoxygenated form of the protein corresponds remarkably well to the free-energy change predicted for the simple transfer of the amino acid side chain at position beta 37 from a hydrophobic to a hydrophilic environment during the dimerization process.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Femoral Head Avascular Necrosis in Heterozygous Sickle Haemoglobin, the Role of Parenteral Drug Abuse: A Case Report

Sickle cell trait is a benign haemoglobin disorder which rarely results in disease or complications. A few cases of osteonecrosis have been reported in the literature in parts of the world with advanced health care system. There are various predispositions to developing avascular necrosis in general, while the sickle beta globin gene inheritance is the most efficient factor. Injection drug abus...

متن کامل

The Role of Helicobacter Pylori in Upper Gastrointestinal Bleeding after Using Ibuprofen in Children Aged 1-14 Years Old

Background Non-Steroidal Anti-Inflammatory Drugs(NSAIDs) including Ibuprofen is one of the most currently used drugs in all age groups and finding the relation between upper gastrointestinal bleeding and Helicobacter pylori (H. pylori) in children who used Ibuprofen, is our topic of research. Materials and Methods During the two years of the study, ten children with upper GI bleeding after Ibup...

متن کامل

The Relationship between Maternal Haemoglobin and Haematocrit with Low Birth Weight and Preterm Labour

Background & aim: Low levels of maternal haemoglobin and haematocrit in the first, second, and third trimesters are considered as possible risk factors regarding low birth weight (LBW) and preterm labour (PTL). The present study aimed to evaluate the relationship between maternal haemoglobin (Hb) and haematocrit (HCT) levels with LBW and PTL. Methods: This cross-sectional study was conducted on...

متن کامل

Absorption Spectra of Normal Adults and Patients with Sickle Cell Anaemia Haemoglobins Treated with Hydrogen Peroxide at Two pH Values

Background: The aim of the present study was application of haemoglobin absorption spectroscopy as a distinguishing tool for identification of two haemoglobin types-HbA and HbS. Material and Methods: Millimolar absorptivities of normal adult haemoglobin (HbA) and sickle cell haemoglobin (HbS) were monitored at pH values of 7.2 and 5.0, within the ultra violet and visible spectral range (250-...

متن کامل

Cholinesterases Enzymes Activities as Biomarkers of Farm Workers Exposed to Organophosphates in Two Communities of Khuzestan, Iran

Organophosphate (OPs) compounds are widely used in intensive agriculture to improve production, protect crops and control diseases vectors. The main mechanism of toxicity of OPs is the inhibition of the Cholinesterase enzymes. In this study the acetylcholinestrase (AChE), butyrylcholinesterase (BChE) and specific acetylcholinestrase (SAChE) activities as potential biomarkers of exposure to OPs ...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • The Biochemical journal

دوره 300 ( Pt 2)  شماره 

صفحات  -

تاریخ انتشار 1994