Nucleation and growth of fibres and gel formation in sickle cell haemoglobin
Article Abstract:
Sickle cell anemia is an inherited disorder which occurs predominantly among people of African heritage. Under conditions of low oxygen tension, the red blood cells take on irregular shapes that resemble sickles; these irregular cells block small blood vessels and cause great pain, tissue damage, and even death. Sickle cell anemia was the first genetic disease in which the actual molecular basis was discovered. The hemoglobin of persons with sickle cell anemia, called hemoglobin S, is altered by the substitution of a single amino acid. This change in chemical structure is sufficient to cause the molecules to clump together when no oxygen is present. Recently, investigators have been able to microscopically monitor the formation of long fibers of hemoglobin S under controlled conditions. Using video-enhanced differential interference contrast microscopy, which permits the visualization of extremely faint specimens, scientists have watched the formation of long strands of hemoglobin S. At first, nothing happens, which indicates that the fiber phenomenon depends upon nucleation. (Nucleation is the process by which a physical change begins at places of irregularity.) Once the fiber formation has nucleated, the fibers grow rapidly, spreading out in all directions from the nucleation center. At this point, a second form of nucleation may be seen; branches observed emerging from growing fibers of hemoglobin indicate that the surface of the fibers themselves can serve as nuclei for the polymerization of more hemoglobin S. The investigators were also able to show that shear forces exerted on the hemoglobin solution promoted nucleation. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1990
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Transplanting a unique allosteric effect from crocodile into human haemoglobin
Article Abstract:
The bicarbonate-ion-binding site which enables the crocodiles to stay under water for long periods is identified by performing experiments with human-crocodile chimaeric hemoglobins. The binding site is located at the alpha 1 beta 2 subunit of the hemoglobin. The transplantation of this site to human hemoglobin reveals that new functions can be introduced into another species which enables the species to survive under conditions hostile to its existence.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1995
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Haemoglobin C protects against clinical Plasmodium falciparum malaria
Article Abstract:
Haemoglobin C was found to be linked with a 29% reduction in risk of clinical malaria in HbAc heterozygotes and 93% of HbCC homozygotes in experiments undertaken on Mossi subjects.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 2001
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