. Biological structure and function; proceedings. Biochemistry; Cytology. 232 TORE HULTIN et al. behind the activation effects described. It may be recalled from the previous section that unexpectedly high incorporation values were often obtained in systems containing mitochondria-free liver homogenates from animals treated with sublethal doses of phalloidin (Fig. 4). This effect could be related to a characteristic modification of the normal time course of the incorporation. In liver systems from animals recovering after amino- fluorene treatment the maximal rate of incorporation may possibly
. Biological structure and function; proceedings. Biochemistry; Cytology. 232 TORE HULTIN et al. behind the activation effects described. It may be recalled from the previous section that unexpectedly high incorporation values were often obtained in systems containing mitochondria-free liver homogenates from animals treated with sublethal doses of phalloidin (Fig. 4). This effect could be related to a characteristic modification of the normal time course of the incorporation. In liver systems from animals recovering after amino- fluorene treatment the maximal rate of incorporation may possibly be reached slightly earlier than usual (Fig. 5), but the quantitative importance 300 CM E E 200 Q. 100-. 0 A 8 12 0^8 minutes of i ncubat ion Fig. 5. Incorporation of [^*C]-L-leucine into protein by mitochondria-free guinea-pig liver homogenates. At zero time, or after 4 or 8 min. of incubation (35 C) o -08 /nmole of [^''C]-L-leucine, 10 /^^moles of PEP and i /xmole of ATP were added. Incubation was interrupted 4 min. later by the addition of TCA. Open bars: control livers. Solid bars: livers from animals given 2-aminofluorene (2-5 mmoles/kg.) 21 hr. prior to decapitation. of this tendency must be fairly limited. As is evident from the time-course curve shown in Fig. i, stimulation effects of the kind discussed here could in principle be due to a prolongation of the active life-span of the micro- somes. However, with the liver preparations from the aminofluorene- treated animals there was no indication of any appreciably longer active period. As is shown by Fig. 5, the increase in incorporation activity was equally pronounced in the period with maximal incorporation rate as in any other incubation period. In cell-free liver systems from adult animals only a limited part of in- corporated, labelled amino acids becomes distributed to the proteins of. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - color
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