Racemization California

Bada, J. L., Master, P. M., Hoopes, E., Darling, The Dating of Fossil Bones Using Amino Acid Racemization, In Radiocarbon Dating, pp. 740-756, Berkeley, University of California Press, 1979. 

Bada, J.L. (1985). Aspartic acid racemization ages of California Paleoindian skeletons. American Antiquity 50 645-647. 

We are grateful to Dr. John H. Cardellina, II, National Cancer Institute, Prof. D. John Faulkner, University of California, San Diego, and Prof. Raymond J. Andersen, University of British Columbia, for kindly providing us with H, l3C NMR spectra of natural clavepictines A, B, Pictamine, and lepadin B. We are also indebted to Dr. Thomas F. Spande, National Institute of Health, for measurement of the GC analysis of synthetic, racemic, and natural quinolizidine 2071 with (3-dextrin chiral column, and to Prof. Andre Rassat, Ecole Normale Superieure, for kindly providing us with racemic quinolizidine 2071. 

A second test compared 50 x 12 mm dispensers made of thinner acrylic film (3- instead of 6-mil) with those of 16-mil polymeric PVC each dispenser contained about 10 mg of synthetic racemic pheromone. These were aged in a California greenhouse as in the previous test, and the lure contents were measured weekly for a 6-week period. The analyses showed similar t /2 values for the 2 formulations 16 days for the 16-mil polymeric PVC and 18 days for the 3-mil acrylic dispensers. 

The final dispenser evaluation with COMB pheromone again compared dispensers made of 3-mil acrylic film with those of 16-mil polymeric PVC the 13 x 13 mm laminate dispensers each contained 1 mg of racemic pheromone. Also included in this test were rubber septa baited with 1 mg of compound. All of the dispensers were aged outdoors in California at temperatures ranging from 32-39°C in the daytime to 15-21°C overnight. Analyses of residual lure contents showed a tof just 2 days for the rubber septa and approximately 15 days for the 16-mil polymeric PVC laminate the 3-mil acrylic dispensers lost pheromone so slowly that tj/2 could not be measured, but it was much greater than 70 days. On the basis of these tests, laminate dispensers made of 16-mil polymeric PVC were selected for the COMB monitoring program and have been successfully used in 1980 and 1981. 

Masters, P. M., and Bada, J. L. (1977). Racemization of isoleucine in fossil molluscs from indian middens and interglacial terraces in Southern California. Earth Planet. Sci. Lett., 37, 173-183. 

IS). The Holocene samples which we investigated came from a variety of localities which diflEered greatly in their general environmental characteristics. If variations in environmental parameters could produce anomalously high racemization, this should have been detected in at least some of the samples which we analyzed. Since the extent of racemization in the Holocene samples from throughout California is consistently much less than in the Del Mar Man skeleton, etc., this indicates that the most reasonable explanation for the highly racemized amino acids in these latter skeletons is that they are considerably older than the Holocene skeletons. 

Table III. Racemization of Aspartic Acid in Holocene Radiocarbon-Dated Aboriginal Skeletons from California...

Table IV. Racemization Ages of Holocene Aboriginal Skeletons from Southern California Coastal Sites ...

These various comparisons demonstrate that the Laguna skull radiocarbon date of 17,150 years is correct, that the dated Laguna material is indeed the original skull, and that the kasp value derived from the racemization and radiocarbon analyses of the Laguna skull can be used to calibrate the amino acid racemization reaction for the southern California coast. 

Racemization Dating of Chione from Indian Middens. The prehistoric inhabitants of coastal southern California left abundant kitchen midden deposits marking their living sites. Mollusc shells are the major constituents found in these middens. We attempted to deduce racemization dates for shell from six archaeological sites along the coast of southern California (20). All of these sites had carbon-14 dates on shell carbonate available for comparison. 

AMS/HEMS system at the University of Arizona, direct counting of three organic fractions of bone from a human skeleton from the Sunnyvale Site in California, previously dated by the amino acid racemization technique at about 70,000 years, resulted in a revised date of between 3500 and 5000 years b.p. 

The metabolism of jasmonic acid itself was investigated using suspension cultures of Eschscholtia California [46]. From cells incubated with racemic jasmonic acid, the major metabolite was isolated and the chemical structure was determined as 11-hydroxyjas-monic acid 11-O-P-D-glucoside. The configuration at C-11 was determined as R by the Horeau-Brooks method. 

The BBE from Eschscholzia califomica (California poppy) is the best-characterized member of this enzyme class due to the availability of an efficient heterologous expression system using Pichia pastoris [158,159]. Moreover, its biochemical properties, structure, and reaction mechanism were thoroughly investigated [160-162]. In addition, the potential of BBE was investigated for biocatalytic applications such as the kinetic resolution of different racemic nonnatural benzylisoquinolines [16,163,164]. 

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