The effect of smectite composition on the catalysis of peptide bond formation.
Clay-catalyzed glycine and diglycine oligomerizations were performed as drying/wetting cycles at 80 degrees C. Two trioctahedral smectites (hectorite and saponite), three pure montmorillonites, a ferruginous smectite, an Fe(II)-rich smectite, and three smectites containing goethite admixture were used as catalysts. Highest peptide bond formation was found with trioctahedral smectites. About 7% of glycine was converted to diglycine and diketopiperazine on hectorite after 7 days. In the case of dioctahedral smectites, highest yields were achieved using clays with a negative-layer charge localized in the octahedral sheets (up to 2% of converted glycine after 7 days). The presence of Fe(II) in clay is reflected in a higher efficiency in catalyzing amino acid dimerization (about 3.5% of converted glycine after 7 days). The possible significance of the results for prebiotic chemistry is discussed.
Bujdák
J
J
Institute of Inorganic Chemistry, Slovak Academy of Sciences, 842 36 Bratislava, Slovakia.
Rode
B M
BM
D000538:Aluminum Silicates / Q000737:chemistry; D001546:Bentonite / Q000737:chemistry; D002384:Catalysis; D019281:Dimerization; D019418:Evolution, Chemical; D005296:Ferrous Compounds; D005765:Gastrointestinal Agents / Q000737:chemistry*; D005998:Glycine / Q000138:chemical synthesis* / Q000737:chemistry; D006033:Glycylglycine / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D017640:Silicates / Q000737:chemistry
D000538:Aluminum Silicates; D005296:Ferrous Compounds; D005765:Gastrointestinal Agents; D017640:Silicates; C013547:hectorite; D006033:Glycylglycine; D001546:Bentonite; C099453:saponite; C033214:Smectite; D005998:Glycine