Obra civil Global 1 12000,0 12000,0 19 Gabinetes y muebles Global 1 15000,0 15000,

our h a n ds ) w hi c h l i mi t e d the a c c e s s of the s o l v e nt t o t h e m e m b r a n e m a t e r ia l, and the a q u e o u s w a s h i n g step. The a q u e o u s w a s h i n g p r o c e d u r e will r e m o v e most of the g a n g - l i o s i d e s and c e r a m i d e p o l y h e x o s i d e s in the orig^inal e x t r a ct . N ot only are t h e s e c a r b o h y d r a t e - c o n t a i n i n g l i p i d s lost in t he a q u e o u s wash, but the a c i d i c p h o s p h o ­ lipids, such as PS, PA and PI are c a r ri ed i n t o the

a qu e o u s pha s e (Nelson, 1972). The d i s a d v a n t a g e of a w a s h i ng p r o c e d u r e in this r e s p e c t are s h o w n by c o m p ar in g the r e s u l t s of m e t h o d III and m e t h o d IV. H i g h e r levels

of PS, DPI and PA were f o u n d using m e t ho d IV t h a n m e t h o d III, in which the only d i f f e r e n c e was the i n c l u s i o n

(method III) and a b s e n c e (method IV) of t he K C l wash. C h l o r o f o r m / m e t h a n o l (1:1 v/v) and r e e x t r a c t i o n with the same s o l v e n t s y s t e m was used in meth o d II which g a ve a r e l a t i v e l y lo w PS r e c o v e r y and a large a m o u n t of heme

(large h e m e spot on TLC). N e l so n (1972) r e c o m m e n d e d a c h a n g e in t he sol v e n t s y s t e m for r e - e x t r a c t i o n as the r e c o v e r e d p r o p o r t i o n s of lipids are the s ame if using the same s o l ve n t s y s te m for r e - e x t r a c t i o n . In m e t h o d V,

r e - e x t r a c t i o n using a d i f f e r e n t s o lvent s y s t e m (C/M 2:1) gave a g r e a t e r r e c o v e r y of PS and total p h o s p h o l i p i d and a r e l a t i v e l y sma l l a m o u n t of heme. Heme is k n o w n to c a t a l y z e a u t o x i d a t i o n of u n s a t u r at e d lipids (van D e e n e n and De Gier , 1974) which w i l l lead t o a loss of p o l y ­

u n s a t u r a t e d l i p i d s , such as PS and PE and a r e l a t i v e i n c r e a s e of the more s a t u r a t e d f r a c t i o n s , such as SM and PC (Dodge and P h i l l ip s, 1966).

C o m p a r i n g the r e s u l t s for I V and V it is a p p a r e n t that neither omitting the i n i t i a l h a e m o l y s i s s t e p nor i n c re a s i n g the s o l v e n t : cell r a t i o i mp ro v e s the

e x t r a c t i o n e f f i c i e n c y . It is not n ec e s s a r y to g r i n d or