Characterization of Helianthus annuus Lipoic Acid Biosynthesis: The Mitochondrial Octanoyltransferase and Lipoyl Synthase Enzyme System

Lipoic acid (LA, 6,8-dithiooctanoic acid) is a sulfur containing coenzyme essential for the activity of several key enzymes involved in oxidative and single carbon metabolism in most bacteria and eukaryotes. LA is synthetized by the concerted activity of the octanoyltransferase (LIP2, EC 2.3.1.181) and lipoyl synthase (LIP1, EC 2.8.1.8) enzymes. In plants, pyruvate dehydrogenase (PDH), 2-oxoglutarate dehydrogenase or glycine decarboxylase are essential complexes that need to be lipoylated. These lipoylated enzymes and complexes are located in the mitochondria, while PDH is also present in plastids where it provides acetyl-CoA for de novo fatty acid biosynthesis. As such, lipoylation of PDH could regulate fatty acid synthesis in both these organelles. In the present work, the sunflower LIP1 and LIP2 genes (HaLIP1m and HaLIP2m) were isolated sequenced, cloned, and characterized, evaluating their putative mitochondrial location. The expression of these genes was studied in different tissues and protein docking was modeled. The genes were also expressed in Escherichia coli and Arabidopsis thaliana, where their impact on fatty acid and glycerolipid composition was assessed. Lipidomic studies in Arabidopsis revealed lipid remodeling in lines overexpressing these enzymes and the involvement of both sunflower proteins in the phenotypes observed is discussed in the light of the results obtained.

USING SUMFLOWER PROTEIN AS A COMPONENT OF FORCEMEATS FOR FROZEN SEMI-PROCESSED MINCED MEAT PRODUCTS

The problem of how to remediate protein deficiency in the human diet can be solved by using new raw material sources or by consuming vegetable proteins, in particular, sunflower protein, more efficiently. Sunflower is high in biologically complete proteins with a wide range of functional properties. This makes it practical to use sunflower protein as a component of forcemeats for frozen semi- processed minced meat products. As this task is highly topical and promising, it has determined the direction of further research. The purpose of the research is to establish how sunflower protein affects the qualitative characteristics of forcemeat for frozen semi-processed minced meat products, and to specify the rational norms of using it in their composition. It has been studied how sunflower protein effects on the moisture-holding capacity of forcemeat. The results have shown a sharp increase in this parameter after introducing sunflower protein. It has been established that sunflower protein affects the processes of freezing and defrosting in forcemeat systems. However, it has no pronounced cryoprotective properties independent of its concentration in a system, and the loss in weight during freezing the samples is but insignificant. Studying the effect of sunflower protein powder on the sensory, functional, and technological properties of forcemeat reveals positive dynamics and direct relationship between these characteristics and the concentration of sunflower protein. The losses in the weight of the semi-processed products during heat treatment have been analysed. The data obtained have shown that this parameter decreases by 1.9 times when sunflower protein is used. Sensory evaluation of the samples has allowed establishing that the rational norm for sunflower protein as a forcemeat component is up to 10%. Thus, the research conducted prove that it is practical to use sunflower proteins as components of forcemeats for frozen semi-processed minced meat products. This will make the products more nutritious, allow controlling their amino acid composition, curtail the expenditure of raw meat, help control the rheological parameters, and expand the range of products.