Year: 1997
Type: dissertation
Abstract: Catalytic DNA molecules for porphyrin metallation were derived by utilizing in f / u r o selection and transition state analog(^^^) technologies.DNA clones were isolated C fronfa random sequence DNA library on the basis of their affinity binding to Nmethylfiesoporphyrin IX (NMM), the proven TSA for porphyrin metallation.Various chemical, enzymatic and physical methodologies were used to successfully identify the 4 binding motifs within these DNA clones.These guanine-rich binding motifs, in isolation.also shoyed high-affinity binding to NMM. *Two selected DNA clones and their binding motifs were first chosen to test for possible metallation activity.The binding site from PS5 was found to be catalytic towards the insertion of Cu(I1) and Zn(I1) into different porphyrins.This DNA enzyme showed several novel features, such as inhibition by M ~" and enhancement by potassium.Catalysis was found to be inhibited by NMM, and followed Michaelis-Menten kinetics at fixed copper concentrations.Values of kc,, of 13.7 hr-', and KM of 2.9, mM, and k,,/k,,,.,, of 1400 for mesoporphyrin LX (MPIX) were initially measured.. A subsequent thorougbfinvestigation of the properties of this DNA enzyme revealed the following: Three related porphyrins were acceptable as the substrates, of ~vhich protoporphyrin LX (PPIX) was preferred over MPIX; a 24-nucleotide sequence (PSS.hl).wasboth the optimal and' the minimal catalytic unit; and no catalytically relevant 9 binding site for copper appeared to exist in the folded structure of the DNAzyme; and, K 'was the only ion needed to suppon catalysis.This DNAzyme, PSS.M, functioned most d
Author: Yingfu Li
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W656731692