TY - JOUR
T1 - Length distributions of hemoglobin S fibers
AU - Briehl, Robin W.
AU - Mann, Eric S.
AU - Josephs, Robert
N1 - Funding Information:
This work was supported by grants HL07451 and HL28203 (to R.W.B.) and HL22654 (to R.J.) from the
Funding Information:
National Heart, Lung and Blood Institute. E.S.M. was supported by a Medical Scientist Training Program award from the National Institute of General Medical Sciences. We thank Joel Hirsch, Colleen Randall, Barry Gross and Patty Wu for technical assistance and Dr Samuel Charache of Johns Hopkins School of Medicine for generous gifts of sickle cell blood.
PY - 1990/2/20
Y1 - 1990/2/20
N2 - Electron microscopy of sickle cell hemoglobin fibers fixed at different times during gelation shows an exponential distribution of fiber lengths, with many short fibers and few long ones. The distribution does not change significantly with time as polymerization progresses. If this distribution of lengths reflects kinetic mechanism of fiber assembly, it complements information from studies of the progress of average properties of the polymers and, as has been done for other rod-like polymerizing systems, permits testing of models for the mechanism of fiber assembly. In this case, the results are consistent with the double nucleation model of Ferrone et al. or with a related alternative model based on fiber breakage. However, other possible causes of this microheterogeneity exist, including: breakage due to solution shearing of the long, rod-like, fibers; the presence of residual nuclei; equilibrium relations governing polymerization; and breakage of solid-like but weak gels that develop early and adhere to the grid. The arguments against the first three of these possibilities suggest that they are not responsible. However, breakage of entanglements or cross-links in a solid-like and adherent gel is consistent with the distributions.
AB - Electron microscopy of sickle cell hemoglobin fibers fixed at different times during gelation shows an exponential distribution of fiber lengths, with many short fibers and few long ones. The distribution does not change significantly with time as polymerization progresses. If this distribution of lengths reflects kinetic mechanism of fiber assembly, it complements information from studies of the progress of average properties of the polymers and, as has been done for other rod-like polymerizing systems, permits testing of models for the mechanism of fiber assembly. In this case, the results are consistent with the double nucleation model of Ferrone et al. or with a related alternative model based on fiber breakage. However, other possible causes of this microheterogeneity exist, including: breakage due to solution shearing of the long, rod-like, fibers; the presence of residual nuclei; equilibrium relations governing polymerization; and breakage of solid-like but weak gels that develop early and adhere to the grid. The arguments against the first three of these possibilities suggest that they are not responsible. However, breakage of entanglements or cross-links in a solid-like and adherent gel is consistent with the distributions.
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U2 - 10.1016/0022-2836(90)90070-3
DO - 10.1016/0022-2836(90)90070-3
M3 - Article
C2 - 2313696
AN - SCOPUS:0025309704
SN - 0022-2836
VL - 211
SP - 693
EP - 698
JO - Journal of Molecular Biology
JF - Journal of Molecular Biology
IS - 4
ER -