Über die Hydrolyse von Dipeptiden in Anwesenheit von Lanthan‐, Cer(III)‐ und Cer(IV)‐Ionen

Abstract

Jahrg. 91 Bei Verseifung mit alkohol. Kalilauge crfolgte Bildung der blaufluoreszierenden Harmancarbonsaure-(3) (Ill). RF-Wert 0.25, Laufmittel 5-prOZ. Ammoniak. Eine qualitative Auswertung des UV-Spektrums des Esters ergab ubereinstimmung mit dem in der Literatur beschriebenen Harmanspektrumzl). A, , , = 236my. 270my; kleinere Maxima A , , , = 33 I my, 345 my. Zum Vergleich wurde die Ausmessung des Harmanspektrums in Methanol wiederholt und die genaue Lage der Maxima bestimmt: A, , , = 212mp, log E = 4.287; 234mp, log E = 4.535; 287.5mp, logc = 4.171; 335mp. loge = 3.607; 348.5my, log& = 3.620 (Methanol, r = 0.0142 bzw. 0.0071 g/l). Die Peptidbindung in Dipeptiden wird in Anwesenheit geeigneter Metallionen gelost. -Der metallionenkatalytischen Spaltung liegt die Bildung eines zerfallsfahigen Reaktionszwischenproduktes durch koordinative Bindung desKatalysators an die freien Elektronenpaare des Amino-und des Carbonamid-Sticksioffes des Dipeptids zugrunde. -Die ,,peptidatische" Wirksamkeit der Katalysatoren nimmt in der Reihenfolge Ce4@ + Ce3@ -+ La3O ab. --Fur die gepriiften Dipeptide ergibt sich eine Stabilitatsreihe, ahnlich wie sie friiher bei der enzymatischen Spaltung und neuerdings bei der Hydrolyse mittels Ionenaustauscher gefunden worden ist.

Major Advances in the Hydrolysis of Peptides and Proteins by Metal Ions and Complexes

“…Interestingly, while 3 helped to reduce Zr IV precipitation, peptide hydrolysis by Zr IV was decreased when Tris was added [35]. This observation led us to speculate that hydrolysis of peptides by Zr IV /4,13-diaza-18-crown-6 might have a heterogeneous component similar to peptide hydrolysis by lanthanide hydroxide gels [64][65][66]80].…”

“…Cerium(IV) is the only lanthanide with an accessible +4 oxidation state and has enhanced Lewis acid strength imparted by its high positive charge density. Thus, it is not surprising that peptide hydrolysis by Ce IV has consistently been found to be superior in comparison to other lanthanide ions (e.g., La III , Ce III , Pr III , Nd III , Sm III , Eu III , Gd III , Tb III , Dy III , Ho III , Er III , Tm III , Yb III ) [64,65,72,80]. This result can be accounted for by the exceptional ability of Ce IV to activate the peptide amide carbonyl towards nucleophilic attack.…”

“…The first, published reports of lanthanide-assisted peptide hydrolysis were in 1956 and 1958 [64,65]. In these early, pioneering studies, Bamann and coworkers treated a series of dipeptides with Ce IV , Ce III , and La III .…”

“…In the peptide hydrolysis reactions described by Bamann and coworkers, the active hydrolytic species were heterogeneous lanthanide hydroxide gels [64,65]. Komiyama then employed γ-cyclodextrin to solubilize Ce IV , and was able to achieve homogeneous hydrolysis of the dipeptide Gly-Phe in 39% yield after 24 h at pH 8.0 and 60 °C [72].…”

“…In the case of Cu II , Co III , Ni II , Pd II , and Pt II , intact proteins have also been cleaved [32][33][34]36,49,50,74,75,82,86,[89][90][91][92][93][94][95][96][97][98]. Although hydrolysis is sometimes accomplished at ~pH 7.0 and 37 °C [34][35][36]41,[47][48][49][50][51][52], either extreme pH, and/or elevated temperatures are ocassionally employed [32,33,[63][64][65][66][67][68][69][70][71][72][73][74][75][76][77][78][82][83]…”