Kinetic study of the appearance of an anti-bacterial peptide in the course of bovine haemoglobin peptic hydrolysis.
The kinetics of the alpha (1-23) peptide, which is the first anti-bacterial peptide to be isolated from a haemoglobin hydrolysate, was studied in the course of peptic hydrolysis at pH 4.5 and 23 degrees C in an homogeneous-phase system. A one-step reversed-phase HPLC coupled with photodiode array detector method was applied to identify and isolate this anti-bacterial peptide. The kinetics of peptide appearance were investigated in acetate buffer alone and in urea as a haemoglobin-denaturing agent. Two different mechanisms, 'one-by-one' for native haemoglobin hydrolysis and 'zipper' for denatured haemoglobin hydrolysis, were observed. Whatever the haemoglobin state, native or denatured, and whatever the hydrolytic mechanism, one-by-one or zipper, the anti-bacterial alpha (1-23) peptide is a transient peptide. To prepare the alpha (1-23) peptide it is suitable to hydrolyse haemoglobin in the presence of urea at a corrected degree of hydrolysis (DH(c)) of 13.5%. The amount of peptide produced in the presence of urea was twice as high as for the hydrolysis of native haemoglobin. The yields of alpha (1-23) peptide with respect to haemoglobin at the optimal DH(c) values were 55 and 25% respectively.
Choisnard
Luc
L
Laboratoire de Technologie des Substances Naturelles, IUT A Lille 1-BP 179, 59653 Villeneuve d'Ascq Cedex, France.
Froidevaux
Renato
R
Nedjar-Arroume
Naïma
N
Lignot
Brigitte
B
Vercaigne-Marko
Dominique
D
Krier
François
F
Dhulster
Pascal
P
Guillochon
Didier
D
D000085:Acetates / Q000737:chemistry; D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry / Q000302:isolation & purification*; D002417:Cattle; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006454:Hemoglobins / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D010434:Pepsin A / Q000737:chemistry; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D013552:Swine; D014508:Urea / Q000737:chemistry
D000085:Acetates; D000890:Anti-Infective Agents; D006454:Hemoglobins; D010446:Peptide Fragments; D014508:Urea; D010434:Pepsin A