fn Partíal Fulfillnent - MSpace

the avail-abilities decrease from corn to wheat and to barley
and is inversely related. to the increase in the proportions of
albunin and globulin from corn to flheat to barley. Protein
from al-bumin and globulin rnakes up approxirn ately 5-6; 9-L5
and 13 -24,4" of the total protein of corn, wheat and barle¡r
respectively (Neurath and Eailey, I95t+). Postel (1957) sue-
gested that since barley has a nulticellular aleurone layer, it
should be higher in aleurone protein as a percentage of total
protein compared wit,h wheat, which has a síng1e al_eurone layer.
SeveraL workers suggested the relatively high concentration of
LïS in aleurone protein to be responsible for its tov; availability
from cereal grains (Eggu¡r, lpll; Iiunck, L96h; Sauer et ù.., I97b).
The above hypothesis explains also the 1ow availabilities of
ASP and Al,A and the high availabilities of GLU and PRO. i{owever,
the high availabilities of ARG and TtfS and the relatively low
availability of THR can not be explained in the sanre menner
(Tables2 and 4).
Other factors may affect protein digestibility and.
therefore amino acid availability from cereal grains. Trypsin
plays an important role j-n the digestion of protein. The extent
of digestion by trypsin can be influenced by the amino acid
sequence near the catalytic site. lrypsin exhibits a strict
specificity for arginyì and 1ysyl peptide bond.s. The nu¡:ber of
peptide bond.s split by trypsin wj-ll be dependent on the total
anount of .A,RG and l,YS present in the protein (lÌilhalyi, L}TZ).
r4