Serine peptidase CLPP is conserved among bacteria, chloroplasts, and mitochondria. In humans and mice, its loss causes Perrault syndrome with growth deficit, infertility, deafness, and ataxia. In the filamentous fungus Podospora anserina, CLPP-loss leads to longevity. CLPP substrates are selected by CLPX, an AAA+ unfoldase. CLPX is known to target delta-amino-levulinic-acid synthase (ALAS) to promote pyridoxal-phosphate (PLP) binding. CLPX may influence cofactor association with other enzymes. Here, the evaluation of P. anserina metabolomics highlighted arginine/histidine reduction. In Mus musculus cerebellum, reductions of Arginine/Histidine and Citrulline occurred with concomitant accumulation of heme-precursor protoporphyrin-IX. This suggests that increased biosynthesis of 5-carbon (C5) chain deltaALA consumes not only C4 succinyl-CoA with C1 glycine but also specific C5 delta amino-acids. As responsible enzymes for these converse effects, elevated abundance of CLPX and ALAS is paralleled by elevation of OAT (PLP-dependent, ornithine-delta-aminotransferase). Possibly as consequence of altered C1 metabolism, CLPP-null cells in P. anserina proteome profiles showed strong accumulation of a methyltransferase and two mitoribosomal large subunit factors. Reduced Histidine levels may explain previously observed metal interaction problems. As main nitrogen-storing metabolite, deficient Arginine would affect the urea cycle and polyamine synthesis. Supplementation of Arginine and Histidine might rescue growth deficits of CLPP-mutant patients.

Aims: To study the effects of pyridoxal phosphate (PLP) on oxidative stress in isolated pancreatic acinar cells. We have previously shown that PLP has cytoprotective and insulinotropic effects on mice islet cells in vivo and in vitro studies. Main methods: Acinar cells were isolated from three months old WNIN male rats and were cultured in vitro for a period of 24 h in CO₂ incubator. Later the cells were divided into four groups as untreated (group 1), H₂O₂ treatment (group 2)_, PLP treatment (group 3) and PLP followed by H₂O₂ treatment (group 4). Cell viability was confirmed using MTT assays, oxidative stress levels were measured with ROS assay, change in different protein levels were recorded by flow cytometry. The acinar cells insulin secretion assay was performed with ELISA. The amylase protein expression was assessed using confocal microscopy. Key findings: The cell viability of acinar cell in group 1 was considered as 100%, while in group 2 it was reduced to 82% due to H₂O₂ effect, and in group 3 (99.8%) and group 4 (99.5%) were near to group 1 due to the cytoprotective effect of PLP. The ROS levels were increased by 1.47 folds in group 2, while PLP decreased to 1.02 fold in group 4, which was comparable with the changes in group 1. Beneficial effects of PLP were also observed from the increased expression levels of acinar cells are amylase -2.01, neurogenin-3-9.51, PDX-1- 23.6 and insulin-13.5 in group 3 compared to group 1. The specificity of PLP’s response was confirmed by amino oxy acetic acid (AOAA), a specific PLP inhibitor. The increased amylase protein localization with PLP was confirmed by confocal microscopy. Insulin secretion efficiency of acinar cells was observed to be 6.13 folds higher at basal and 24.63 fold higher at stimulated levels in group3 compared to group1. Significance: Our results advocate the antioxidant and cytoprotective effects of PLP on the pancreatic acinar cell along with increased pancreatic marker expressions of amylase,PDX-1, neurogenin-3 and insulin proteins.

The reconstruction of traffic accidents has grown as an interdisciplinary field since the first accident occurred. Various methods have been developed over time, starting with primary data collected at the scene of the accident. In this work, I proposed a method by which the value of the force in the safety belt buckle can be determined when it is equipped with a pretensioning system with pyrotechnic trigger in the tube, PBP or PLP type. The anti-return system of the pretensioner mechanism, which prevents the passenger's body from moving forward, contains a set of balls that block the movement of the piston in the pretensioner tube after its activation. When limiting the movement, the force the human body exerts on the safety belt webbing is transformed into the deformation of the pretensioner tube by the balls of the anti-return system. Depending on the magnitude of the force, the marks left by the balls differ. I propose a relationship of dependence between the acting force and the deformation of the tube. An experimental test bench was created to perform shock traction tests on the pre-tensioning system, under similar conditions to those of the human body acting on the belt in case of a frontal collision. Following the tests, the force value of the seat belt buckle cable and the diameter of the spherical indentations that the balls left in the pretensioner tube were measured. A mathematical model was proposed to determine the normal force with which a ball from the anti-return system deforms the tube. The normal force was also determined by two other methods specific to contact mechanics and used in the specialized literature. By comparing the normal forces obtained by the three methods, a good correlation between the proposed mathematical model and the Komvopoulos-Ye method resulted, the "Hardness" method not being suitable for this study. The determined polynomial regression curve allows finding out the force in the cable of the closer depending on the size of the deformations produced by the balls in the tube. The forces in the belt webbing can be thus determined and biomechanics specialists can evaluate the injuries to the chest and abdomen of the occupants of a vehicle.

Enzymes reliant on pyridoxal 5'-phosphate (PLP), the metabolically active form of vitamin B6, hold significant importance in both biology and medicine. They facilitate various biochemical reactions, particularly in amino acid and neurotransmitter metabolisms. Vitamin B6 is absorbed by organisms in its non-phosphorylated form and phosphorylated within cells by pyridoxal kinase (PLK) and pyridox-(am)-ine 5'-phosphate oxidase (PNPOx). The flavin mononucleotide dependent PNPOx enzyme converts pyridoxine 5'-phosphate and pyridoxamine 5'-phosphate into PLP. PNPOx is vital for both biosynthesis and salvage pathways in organisms producing B6 vitamers. However, for those depending on vitamin B6 as nutrient, PNPOx participates only in the salvage pathway. Transferring PLP produced by PNPOx to client apo-enzymes is indispensable for their catalytic function, proper folding and targeting to specific organelles. PNPOx activity deficiencies due to inborn errors lead to severe neurological pathologies, particularly neonatal epileptic encephalopathy. PNPOx enzymes from different organisms maintain PLP homeostasis through highly regulated mechanisms, including structural alterations throughout the catalytic cycle and allosteric PLP binding influencing substrate transformation at the active site. Despite shared features, species-specific regulations are evident among PNPOx enzymes.