BANGLADESH JOURNAL OF BIOCHEMISTRY

Bangladesh Journal of  Biochemistry
AN INTERNATIONAL JOURNAL IN BIOCHEMICAL SCIENCE

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Bangladesh Journal of Biochemistry, Vol. 3, No. 2, 45-52, December 1997
MULTIPLE FORMS OF DIHYDROFOLATE REDUCTASE IN LEUKOCYTES OF CANCER PATIENTS WITH NON-HEMATOLOGICAL MALIGNANCIES

M. Perwaiz IQBAL, Fakhra SULTANA, Naseema MEHBOOBALI, N. Ikram A. BURNEY, Tariq SIDDIQUI and M. Anwar WAQAR
Departments of Biochemistry and Medicine, The Aga Khan Univertity, Stadium Road, Karachi-74800, Pakistan  

(Received April 16, 1998)

Abstract
An immunoreactive form of dihydrofolate reductse, which is different from the active enzyme, has been identified in large quantity in leukocytes of cancer patients with different types of non-hematological malignancies by using enzyme linked immunosorbent assay (ELISA). The size of this immunoreactive but apparently non-functional enzyme is larger than the active dihydrofolate reductase.This protein with antegenic homology to dihydrofolate reductase present in leukocytes of a patient with Adenocarcinoma and a patient with Hodgkin’s disease could be converted into small size proteins having no enzyme activity by using  4M urea and 40mM dithioerythritol. However, the protein present in the leukocytes of patients with non Hodgkin’s lymphoma and small cell lung carcinoma could not be dissociated into small size proteins suggesting a heterogeneity in the structure of this protein in different types of cancer.

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Bangladesh Journal of Biochemistry, Vol. 3, No. 2, 53-68, December 1997
CHEMICAL MODIFICATIONS OF LUFFIN-a, A RIBOSOME INACTIVATING PROTEIN FROM LUFFA CYLINDRICA SEEDS- THE INVOLVEMENT OF HIS-140 AND TYR-165 IN ITS ACTIVITY

M. Rafiqul ISLAM, M. Ahad ALI and Gunki FUNATSU
Laboratory of Protein Chemistry and Engineering, Faculty of Agriculture, Kyushu University, Fukuoka 812, Japan 

(Received June 16, 1998)

Abstract
Luffin-a present in the seeds of sponge gourd appeared to be one of the strongest ribosome inactivating proteins (RIPs). In order to identify the residues in the active center of this molecule, we modified luffin-a with amino acid specific reagents. The only tryptophan residue in luffin-a was inert towards N-bromosuccinimide oxidation. Four arginine residues were rapidly modified  with excess of phenylglyoxal, but only 60% loss in activity indicated that arginine residues are not located in the active center of this protein. Carbodiimide rapidly esterified 11 carboxyl groups in luffin-a with concurrent complete loss of activity, suggesting that one or more of these residues might be involved in enzymatic activity. Treatments with excess N-[(iodoacetyl)  amino-ethyl]-5-naphthylamine-1-sulfonic acid and 1mM diethylpyrocarbonate modified the single histidine residue (His-140) present in luffin-a without alteration of other residues. Modification of this His residue reduced luffin’s protein synthesis inhibitory (PSI) activity to only 8%. Treating luffin-a with excess  N-acetylimidazole acetylated 4 tyrosine residues and decreased  its PSI-activity to 14%. A similar extent  of activity loss was also observed when 1.3 tyrosine residues per mol in luffin-a was iodinated with excess of KI
3. Isolation and sequencing of the readioiodinated tryptic peptides from [125]luffin-a revealed Tyr-165 as the major radioactivity containing residue. These results suggests that His-140 and Tyr –165 are critical for the PSI-activity of luffin-a.

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Bangladesh Journal of Biochemistry, Vol. 2, No. 1, 69-74, December 1997
CARDIOACTIVE AND ANTIPYRETIC ACTIVITY OF SOLANUM XANTHOCARPUM

A.S. Shamsur ROUF, Biplob K. MITRA,and Joydeb K. KUNDU,  
Department of Pharmacy. Department of Biochemistry, 
M. Aftab UDDIN
University of Dhaka, Dhaka-1000, Bangladesh 

(Received  February 22, 1998)

Abstract
The effect of petroleum ether, ethylacetate and methanol extracts of Solanum xanthocarpum on toad heart muscle was studied. The effect of the petroleum ether extract on toxin-induced pyrexia in rabbits was also studied. The petroleum ether and methanol extracts were found to increase heart rate significantly while ethylacetate extract and standard drug digoxin caused a significant decrease in the heart rate. A significant increase in cardiac muscle contractility was observed with ethylacetate and methanol extracts whereas a significant decrease in contractility was caused by petroleum ether extract. The petroleum extract caused a lowering of temperature index in toxin induced pyrexia, indicating antipyretic activity of the petroleum extract.

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Bangladesh Journal of Biochemistry, Vol. 3, No. 2, 75-86,  December 1997
MODULATION OF HUMAN NEUTROPHIL FUNCTIONS BY VIBRIO CHOLERAE LIPOPOLYSACCHARIDE 

Laila N. ISLAM, Kazi Mokim AHMED and Shahnaj SHAMMY
Department of Biochemistry, University of Dhaka, Dhaka-1000, Bangladesh

(Received May 18, 1998) 

Abstract
The locomotor response of human neutrophils to lipopolysaccharide (LPS, commonly known as endotoxin) of Vibrio cholerae Inaba 569B was studied using a polarization assay on cells in suspension and compared to that induced by N-formyl-methionyl-leucyl-phenylalanine (FMLP).The test LPS induced morphological polarization in neutrophils and hence was a chemostimulant. Neutrophils were pretreated with an optimal of LPS and its effects upon their adhesion, locomotion, nitro blue tetrazolium (NBT) dye reduction and phagocytic activity were tested. The results showed that the LPS inhibited neutrophil phagocytosis of opsonized yeast but not of the unopsonized yeast. The inhibitory effect on phagocytosis by Vibrio endotoxin challenged neutrophils was retained after thorough washing of the cells. On the contrary, uniform concentration of the LPS stimulated the neutrophils to exhibit increased random locomotion (chemokinesis) through cellulose nitrate filters. Furthermore, the endotoxin stimulated the neutrophil to reduce NBT dye and increased neutrophil adhesion to clean glass. These results suggest that LPS of V. cholerae binds to neutrophils, cause membrane alteration and hyperadhesion of the cells which interfere with the C3b-and/or Fc-receptor mediated phagocytic activity of the cells and thus modulate neutrophil functions.  

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Bangladesh Journal of Biochemistry, Vol. 3, No. 2, 87-93,  December 1997
RELATIONSHIP OF GLYOXYLASE-1 ACTIVITY WITH REGENERATION POTENTIAL OF EMOBRYO-DERIVED RICE CALLUS 

M. Moksed ALI, Zahidul ISLAM, Mohammad ALI, Noorain M. RASUL, N. Tasnim FARZANA, M. Omar FARUQUE, Zeba I. SERAJ  and Ishtiaq MAHMUD
Department of Biochemistry, University of Dhaka, Dhaka-1000, Bangladesh 

(Received October 14, 1997)   

Abstract
Glyoxalase-1 activity of 21-day old calli from nine different rice varieties was found to be inversely proportional to their regeneration potential. The regeneration potential of rice calli was identified as high, intermediate or low based on regeneration per cent and number of plantlets regenerated per embryo. The differences in glyoxalase-1 activity were significant at the 5% level as judged by Duncan’s Multiple Range Test. Seven and 14-day old calli of four of the above varieties with high and poor regeneration were also assayed for glyoxalase-1 activity. Enzyme activities of the highly regenerative and poorly regenerative calli are low at 7 days but increase significantly at 14 days with no statistical difference between the high and poor groups. However, the enzyme activity for the calli in the high group decreases at 21 days whereas the activity of the calli in the poor group remains high.

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Bangladesh Journal of Biochemistry, Vol. 3, No. 2, 95-98, December 1997
IN VITRO REGENERATION OF SIX INDICA RICE CULTIVARS

Mariam NASREEN and M. Anwar HOSSAIN
Department of Biochemistry, University of Dhaka, Dhaka-1000, Bangladesh. 

(Received September 14, 1997)

Abstract
The regeneration capacities of six selected Indica rice (Oryza sativa L.) cultivars were studied through callus culture initiated from mature seeds. Mature seeds of these varieties were used for callus induction. Plantlets were obtained from the induced callus. Regeneration was found to be the highest (100%) for BR-5 and the lowest (40%) for FR13A. Highest number of plants per seed were obtained from BR-20 (23) and lowest from BR-5 (3).
                                

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