FIG. 1.
Outline of the two novel procedures for determination of chitin cross-links. In both cases chitin was specifically labeled in vivo with [14C]glucosamine and estimated in the various fractions by radioactivity measurement. For details of the procedures, see Materials and Methods. (A) Curdlan method. Free chitin was determined from the unbound radioactivity (step 1). This value was subtracted from the unbound radioactivity (step 2) to obtain the chitin attached to β(1-6)glucan. The chitin bound to β(1-3)glucan can be calculated by subtracting the unbound value (step 2) from the total or by determining the bound radioactivity (step 2). (B) Chitosan method. Each step 1 to 4 was performed on the insoluble residue remaining from the preceding step. The radioactivity of each extract was measured.