Structure and spectroscopy of methionyl-methionine for aquaculture

Abstract

The amino acid l-methionine is an essential amino acid and is commonly used as a feed supplement in terrestrial animals. It is less suitable for marine organisms because it is readily excreted. It is also highly water soluble and this results in loss of the feed and eutrophication of the water. To address these problems, the dipeptide dl-methionyl-dl-methionine (trade name: AQUAVI Met-Met) has been developed as a dedicated methionine source for aquaculture. The commercial product is a mixture of a racemic crystal form of d-methionyl-d-methionine/l-methionyl-l-methionine and a racemic crystal form of d-methionyl-l-methionine/l-methionyl-d-methionine. In this work, we have computationally, structurally, spectroscopically and by electron microscopy characterised these materials. The microscopy and spectroscopy demonstrate that there is no interaction between the dd–ll and dl–ld racemates on any length scale from the macroscopic to the nanoscale.

Raman spectroscopy in cell biology and microbiology

“…Band 17 at ~792 cm −1 has been indicated as a direct measure of the relative quantity of nucleic acid present in the culture. [ 352 ] Band 15, which can be assigned to carboxylate O–C–O in‐plane bending of methyonilmethionine, [ 296 ] is instead related to biofilm formation. This assignment is supported by the appearance of two new bands at ~684 and 773 cm −1 (labeled as Bands 7* and 15*, respectively), which can also be assigned to molecules belonging to the biofilm (cf.…”

“…The Raman spectra were deconvoluted into Voigtian band components (labeled from 1 to 18). The precise wavenumbers of the deconvoluted sub‐bands and their tentative assignments [ 23,59,63,274–297 ] are given in Table S3.…”

“…Tentative assignments for the deconvoluted band components, according to labels given in the spectra of Figure 44, are offered in Table S4. [23,40,41,45,109,261,275,[295][296][297]340,[348][349][350][351][352] Vibrational assignments were given according to the above-described chemical composition of the biofilm.…”

Optimal DL-Methionyl-DL-Methionine Supplementation Improved Intestinal Physical Barrier Function by Changing Antioxidant Capacity, Apoptosis and Tight Junction Proteins in the Intestine of Juvenile Grass Carp (Ctenopharyngodon idella)

“…Consequently, decreasing the leaching rate of purified AAs would enhance their utilization. DL-methionyl-DL-methionine dipeptide (Met-Met) has low water solubility and high hydrothermal stability, and can be cleaved enzymatically by fish under physiological conditions to provide free D- and L-methionine, and thus it has been used as a methionine supplement for aquaculture to reduce the leaching losses of methionine [ 11 ].…”