Electrospray mass spectrometric characterization of hemoglobin Q (Hb Q-India) and a double mutant hemoglobin S/D in clinical samples.
OBJECTIVE
The clinical analysis of hemoglobin by ion exchange chromatography can result in ambiguities in identification of the nature of the globin chain present in patient samples. LC/ESI-MS provides rapid and precise determination of globin chain masses.


METHODS
Hemolysate of hemoglobin Q-India and hemoglobin S/D/F have been analyzed using ESI-MS. Tandem-MS has been used to establish mutation in alpha chain of hemoglobin Q.


RESULTS
The identification of hemoglobin Q-India is readily achieved by LC/ESI-MS, which establishes the presence of a mutant alpha chain differing in mass from normal alpha chain by 22 Da. The site of mutation has been identified by tandem-MS analysis of a tryptic fragment encompassing residues alphaV62-K90. LC/ESI-MS screening has also provide an example of simultaneous occurrence of mutant globin chains containing beta6E-->V (Hb S, sickle) and beta121E-->Q (Hb D) variant. Expression of gamma(G) globin chain is also demonstrated in this sample.


CONCLUSIONS
The site of mutation in hemoglobin Q-India is identified as alpha64D-->H which differs from mutations alpha74D-->H in Hb Q-Thailand and alpha75D-->H in Hb Q-Iran. Mass spectrometric analysis of hemoglobins from a patient and her parents suggests inheritance of mutant beta globin genes from both parents.
Mandal
Amit Kumar
AK
Molecular Biophysics Unit, Indian Institute of Science, Bangalore-560012, India.
Bisht
Shveta
S
Bhat
Vijay S
VS
Krishnaswamy
Patnam Rajagopalan
PR
Balaram
Padmanabhan
P
D000595:Amino Acid Sequence; D000740:Anemia / Q000097:blood / Q000175:diagnosis; D001774:Blood Chemical Analysis / Q000379:methods*; D004252:DNA Mutational Analysis / Q000379:methods; D003920:Diabetes Mellitus / Q000097:blood / Q000175:diagnosis; D006451:Hemoglobin, Sickle / Q000737:chemistry* / Q000235:genetics; D006455:Hemoglobins, Abnormal / Q000737:chemistry* / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D013789:Thalassemia / Q000097:blood / Q000175:diagnosis
D006451:Hemoglobin, Sickle; D006455:Hemoglobins, Abnormal; D050505:Mutant Proteins; C048600:hemoglobin Q India; C032001:hemoglobin D