Hb Toyoake	beta142(H20)Ala->Pro

CONTACT		External; central cavity; 2,3-DPG pocket
HEMATOLOGY		Normal Hb level but persistent hemolysis in the heterozygote
ELECTROPHORESIS		A diffuse band is observed between Hb A and Hb A2 at alkaline pH
CHROMATOGRAPHY		Hb X was isolated by DEAEcellulose chromatography; Hb X elutes between Hb A and Hb A2
STRUCTURE STUDIES		Tryptic digestion of betaX chain; separation of peptides by fingerprinting; amino acid analysis; sequencing
DNA ANALYSES		Not reported; presumed mutation GCC->CCC at codon 142
FUNCTION STUDIES		Increased oxygen affinity; decreased cooperativity; normal Bohr effect
STABILITY		Unstable
OCCURRENCE		Found in a 21-year-old Japanese male but not in the parents
OTHER INFORMATION		Quantity in the heterozygote perhaps 28%; the variant readily loses heme

REFERENCES
1.		Ohba, Y., Miyaji, T., Hattori, Y., Fuyuno, K., and Matsuoka, M.: Hemoglobin, 4:307, 1980.
2.		Hirano, M., Ohba, Y., Imai, K., Ino, T., Morishita, Y., Matsui, T., Shimizu, S., Sumi, H., Yamamoto, Ki., and Miyaji, T.: Blood, 57:697, 1981.

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This material is from the book A Syllabus of Human Hemoglobin Variants (1996) by Titus H.J. Huisman, Marianne F.H. Carver, and Georgi D. Efremov, published by The Sickle Cell Anemia Foundation in Augusta, GA, USA. Copyright © 1996 by Titus H.J. Huisman. All rights reserved. Neither this work nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, microfilming and recording, or by any information storage and retrieval systems, without written permission.