HEMOGLOBIN, 5 ( 5 ) , 481-486 (1981)

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HEMOGLOBIN DUAN, cx75(EF4) ASP+ALA, A NEW VARIANT FOUND I N CHINA

Dur ing a t e s t i n g survey c a r r i e d o u t i n t h e Duan d i s t r i c t o f Quangxi province i n 1979, a slowly-moving abnormal hemoglobin v a r i a n t was found i n a male o f t h e Zhuang e thn ic group. t u r a l ana lys i s showed i t t o be a p rev ious l y unreported v a r i a n t which we named Hb Duan and has t h e s t r u c t u r e a75(EF4) AsptAla. We r e p o r t here t h e r e s u l t s o f t h e s t r u c t u r a l analyses o f t h i s va r ian t .

Struc-

The proposi tus was a hea l thy 43-year-old male. H i s hemato- l o g i c a l data were as fo l l ows : PCV 0.48 1/1; MCV 95.6 f l ; MCH 24.9 pg; and MCHC 26.0 g/dl . A l k a l i denaturat ion t e s t showed 0.75% Hb F. No i n c l u s i o n bodies were found i n t h e r e d b lood c e l l s . Family s tud ies showed t h a t t h e mother and t h e two daughters o f t h e proposi tus a re a l s o Hb Duan heterozygotes.

Hb 12.5 g/dl ; RBC 5.05 x 1 O I 2 / 1 ;

Target c e l l s were absent.

Ce l l u lose acetate membrane e lec t rophores i s o f t h e hemoglobin s o l u t i o n i n TEB b u f f e r , pH 8.6, showed an abnormal band between t h a t o f Hb A and Hb A2 (F ig. 1, Hb X ) amounting t o 24.8% o f t h e t o t a l hemoglobin content by densi tometr ic measurement. A r a t h e r f a i n t abnormal band (Hb A z - X ) , which moves more s low ly than Hb Ap, was seen. I t amounted t o 1.6% o f t h e t o t a l . The Hb A2 content o f t h e p ropos i tus was 2.6%.

Globin was prepared from t h e hemolysate by t h e acid-acetone method (1). Chain separat ion on c e l l u l o s e acetate membrane e lec t rophores i s (2) shoved i t t o be a slowly-moving c1 cha in va r ian t . The abnormal cx chain was then i s o l a t e d on a prepara- t i v e scale by t h e method o f Clegg -- e t a l . ( 3 ) us ing a CM-cellulose (CM-23) chromatographic column. Next , t h e ax chain was amino-

Received: March 11, 1981; Accepted: A p r i l 14, 1981.

481

Copyright 0 1981 by Marcel Dekker, Inc.

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482

FIGURE 1

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Ce l lu lose acetate e lec t rophores i s o f hemoglobin s o l u t i o n s i n TEB b u f f e r , pH 8.6. Upper: normal. Lower: Hb Duan heterozy- gote.

e thy la ted (AE-crx). F i n g e r p r i n t i n g was c a r r i e d out a f t e r t h e A E a x chain was hydrolyzed w i th DPCC t r e a t e d t r y p s i n (Sigma, type X I ) a t pH 8.0-8.2 and a t 3OoC f o r 3 hours. The i n s o l u b l e core was removed by c e n t r i f u g a t i o n and t h e supernatant was l y o - p h i l i z e d .

ven t iona l procedures; t h e paper e lec t rophores i s was c a r r i e d out at, pH 4.7 and 1500 V for 2.5 hours. t h e absence o f t h e aT-9 pep t ide a t i t s normal p o s i t i o n (Fig. 2 ) , and t h e appearance o f two new spots more cathodic than a normal aAT-9 and w i th h igher chromatographic m o b i l i t i e s (F ig . 2 , spo ts 2 and 2 ' ) . o f aAT-9 and o f spots 2 and 2 ' i s o l a t e d from t h e f i n g e r p r i n t a re g iven i n Table I. a c i d and t h e presence o f one more a l a n i n e i n bo th spot 2 (axT-9) and spot 2' (axT-9 ox id ized) , i n comparison wi th aAT-9.

The f i n g e r p r i n t i n g o f t h e t r y p t i c d iges t was done by con-

The f i n g e r p r i n t revealed

The r e s u l t s o f analyses o f t h e amino a c i d composi t ion

They show t h e absence o f an a s p a r t i c

I n order t o a s c e r t a i n which a s p a r t i c a c i d or asparagine res idue was s u b s t i t u t e d , aAT-9 and aXT-9 were subjected t o t h e r m o l y t i c h y d r o l y s i s according t o Ambler and Meadway (4 ) , fo l lowed by f i n g e r p r i n t i n g (5) . The d i g e s t o f aXT-9 lacked t h e normal pep t ide corresponding t o res idues a73-79 and contained two new pept ides [aX73-79 and aX73-79 (ox)] , which were more cathodic than t h e corresponding fragments o f t h e d T - 9 pept ide (F ig . 3 ) . The

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FIGURE 2

48 3

F i n g e r p r i n t o f t he t r y p t i c hydro lysate o f t h e AE-ax chain. Spots 2 and 2’ are abnormal aT-9 peptides; 2 i s aXT-9 and 2 ‘ i s aXT-9 (ox id ized) .

amino a c i d analyses o f t he d 7 3 - 7 9 and aX73-79 fragments (Table 11) showed t h e l o s s o f one a s p a r t i c a c i d and t h e presence o f one more a lan ine i n t h e abnormal spot. Thus, a lan ine i s s u b s t i t u t e d f o r a s p a r t i c a c i d i n e i t h e r p o s i t i o n 74 o r 75.

Sequence ana lys i s by Edman degradat ion wi th double coupl ing 4-NN-dimethylaminoazobenzene 4’ - isoth iocyanate and phenyl iso- th iocyanate (6,7) showed t h e sequence Val Asp Ala... i n comparison w i th t h a t o f t h e normal sequence Val, A T A S p,... i n d i c a t e d t h a t t h e a s p a r t i c a c i d i n p o s i t i o n a75(EF4) o f t h e hemoglobin v a r i a n t was s u b s t i t u t e d by an alanine. has no t been repor ted prev ious ly . I t i s named Hemoglobin Duan for t h e d i s t r i c t where t h i s v a r i a n t was f i r s t discovered. I t i s represented as a75(EF4) AspA la .

- These r e s u l t s

This v a r i a n t

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484 SHORT COMMUNICATION

TABLE I

Amino A c i d Composi t ion o f Pept ides aAT-9, aXT-9, and axT-9 (Oxid ized)

Molar R a t i o Amino A c i d

R es i due as-9 aXT-9 aXT-9 (ox )

ASP Thr

Ser

Pro

Ala

Val

M e t

Leu

LYS H i s

6.01 (6 )

1.09 (1)

2.24 ( 2 )

1.24 (1)

7.12 (7 )

2.85 (3 )

0.76 (1)

4.10 ( 4 ) 1.01 (1)

2.62 ( 3 )

5.45 (5 )

1.29 (1) 2.09 (2)

0.95 (1)

7.78 (8 )

2.69 (3 )

0.77 (1)

4.38 (4 )

1.03 (1)

2.70 (3)

5.21 (5)

1.41 (1)

2.34 (2 )

0.87 (1)

7.60 (8 )

2.68 (3)

0.79 (1)

4.30 ( 4 ) 1.07 (1)

2.73 ( 3 )

T - 9 aDuan

0 80-82

0 86-87

0 70-72

aDuan73-79

aDuan 73-79

0 6 6 - 6 9

62-65

- 0 + FIGURE 3

F i n g e r p r i n t o f t h e t h e r m o l y t i c d i g e s t o f aXT-9.

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SHORT COMMIJNI CATION 485

TABLE I1

Amino Acid Composition o f Pept ides aA73-79 and ~1x73-79

Amino Ac id Residue

Molar Ra t io

ax73-79 A a 73-79

Val

ASP Met

Pro

Ala

0.81 (1)

3.10 (3)

0.86 (1)

0.92 (1) 1.28 (1)

0.79 (1)

2.30 (2)

0.74 (1)

1.25 (1)

1.84 ( 2 )

Aspar t i c a c i d i n p o s i t i o n 75 o f t h e a chain i s an ex te rna l residue, and i t s replacement l i k e l y w i l l no t cause a f u n c t i o n a l change t h a t g ives c l i n i c a l mani festat ion. wi th s u b s t i t u t i o n s i n p o s i t i o n a75 are Hb 4- I ran [a75(EF4) A s p H i s ] (8) , Hb Winnipeg [a75(EF4) A s p T y r ] (9), Hb Matsue-Oki [a75(EF4) AspAsn] ( l o ) , and Hb Mizushi [a75(EF4) AsptGly] (11). None o f these show any c l i n i c a l mani festat ion. Our case i s no exception.

Department o f Biochemistry and Molecular B io logy Chen Song-Sen I n s t i t u t e o f Basic Medical Sciences J i a Pei-Chen Chinese Academy o f Medical Sciences Wang Lin-Fang B e i j i n g , People's Republ ic o f China

Department o f Medical Genetics I n s t i t u t e o f Basic Medical Sciences Chinese Academy o f Medical Sciences B e i j i n g , People's Republic o f China

Medical Col lege o f Quangxi and Duan County Hosp i ta l Lung Gui-Fang Quangxi, People's Republic o f China

The repo r ted v a r i a n t s

L iang Chih-Chuan

Luo Hui-Yuan L i u Guo-Yang

L iang Shie

Yu Chang-Min Zhuang Li-Zhao L iang Bao-Luan Tang Zhi-Ning

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486

1.

2 .

3 .

4.

5.

6 .

7 .

0.

9 .

10.

11.

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REFERENCES

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Ambler, R.P., and Meadway, R.J., Biochem. J . , 108:893, 1968.

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