PubMed Health⌕ Search

PubMed · 3093873

Enkephalin conformation in solution: a perspective from vibrational spectroscopic studies.

Abstract

The source did not provide an abstract. Follow the original record for more information.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

V Renugopalakrishnan, T W Collette, L A Carreira, R S Rapaka. 1986. Enkephalin conformation in solution: a perspective from vibrational spectroscopic studies.. https://pubmed.ncbi.nlm.nih.gov/3093873/

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

Fragmentation of leucine enkephalin as a function of laser fluence in a MALDI TOF-TOF.

The effects of laser fluence on ion formation in MALDI were studied using a tandem TOF mass spectrometer with a Nd-YAG laser and alpha-cyano hydrocinnamic acid matrix. Leucine enkephalin ionization and fragmentation were followed as a function of laser fluence ranging from the threshold of ion formation to the maximum available, that is, about 280-930 mJ/mm2. The most notable finding was the appearance of immonium ions at fluence values close to threshold, increasing rapidly and then tapering in intensity with the appearance of typical backbone fragment ions. The data suggest the presence of two distinct environments for ion formation. One is associated with molecular desorption at low values of laser fluence that leads to extensive immonium ion formation. The second becomes dominant at higher fluences, is associated initially with backbone type fragments, but, at the highest values of fluence, progresses to immonium fragments. This second environment is suggestive of ion desorption from large pieces of material ablated from the surface. Arrhenius rate law considerations were used to estimate temperatures associated with the onset of these two processes.

Enkephalin, Leucine↗

Reactions of hydrogen atoms with met-enkephalin and related peptides.

The reactions of hydrogen atoms with enkephalins and related peptides have been investigated by radiolytic methods in aqueous solutions and lipid vesicle suspensions. Pulse radiolysis experiments indicate that methionine residue (Met) is the main target. In Met-enkephalin (Tyr-Gly-Gly-Phe-Met) the attack of the hydrogen atom occurs to about 50 % on Met with formation of methanethiyl radical. The remaining percentage is divided roughly evenly between Tyr and Phe. With Leu-enkephalin (Tyr-Gly-Gly-Phe-Leu) the site of attack is limited to Tyr and Phe. Using a peptide-liposome (that is, 1-palmitoyl-2-oleoyl phosphatidylcholine vesicles) model, the cis-trans isomerization of phospholipids could be detected due to the catalytic action of thiyl radicals. The radiation chemical yields of the H(.) and, consequently of CH(3)S(.) radical, was modulated by the experimental conditions and the nature of peptide. Large amounts of trans lipids observed in phosphate buffer vesicle suspensions indicated the efficient role of double-bond isomerization as marker of Met-containing peptide damage.

Enkephalin, Leucine↗

Combination of sustained off-resonance irradiation and on-resonance excitation in FT-ICR.

Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry is becoming more widely used among the mass spectrometric techniques and has excellent figures of merit. Ion activation and fragmentation via sustained off-resonance irradiation (SORI) collision-induced dissociation (CID) is commonly used in FT-ICR. However, one of the limitations of SORI-CID is that only low-energy processes are typically observed in the product ion spectra. Here we present another option for performing CID in FT-ICR, a combination of SORI and on-resonance excitation (RE), termed SORI-RE. In comparison to SORI, this method produces more abundant ions resulting from higher energy fragmentation pathways. The result is the observation of a significant abundance of both higher and lower energy fragmentation pathways in the same mass spectrum. The comparison of SORI, RE, and SORI-RE spectra may lead to mechanistic insights as the relative abundances of certain fragment ions change as a function of internal energy deposition. This technique is simple to incorporate in existing instruments, does not require hardware or software modification, and requires only an additional 20-40 ms acquisition time. The technique is illustrated for a peptide (YGGFL), two disaccharides differing in the position of the glycosidic linkage (2alpha-mannobiose, 3alpha-mannobiose), an oligosaccharide (Alditol XT), a small protein (ubiquitin), and an inorganic cation (UO2+). Examples of higher energy fragmentation pathways enhanced by SORI-RE include the formation of immonium ions and oligosaccharide cross-ring cleavages.

Enkephalin, Leucine↗