Biodegradation of nitriles derived from glucosinolates in rapeseed meal by BnNIT2: a nitrilase from Brassica napus with wide substrate specificity

The Effect of the Glucosinolate Sinigrin on Alterations in Molecular Biomarkers of the Myocardium in Swiss Mice

Glucosinolates are chemically stable compounds that exhibit biological activity in the body following hydrolysis catalyzed by the enzyme myrosinase. While existing in vitro and in vivo studies suggest that the hydrolysis products of glucosinolates predominantly exert beneficial effects in both human and animal organisms, some studies have found that the excessive consumption of glucosinolates may lead to toxic and anti-nutritional effects. Given that glucosinolates are primarily ingested in the human diet through dietary supplements and commercially available cruciferous vegetables, we investigated the in vivo effects of the glucosinolate sinigrin on molecular markers in the myocardia of healthy Swiss mice. This study aims to elucidate whether sinigrin induces positive or negative physiological effects in mammals following consumption. The alterations in myocardial parameters were assessed by measuring metabolic, inflammatory, structural, and antioxidant markers. Our findings revealed that subchronic exposure to sinigrin in the myocardia of female mice resulted in a significant increase (p ≤ 0.05) in the levels of the myokine irisin, matrix metalloproteinases (MMP-2, MMP-9), catalase (CAT), and total glutathione (tGSH), alongside a marked decrease (p ≤ 0.05) in the levels of atrial natriuretic peptide (ANP), compared to the control group consisting of both female and male mice. These results suggest that the hydrolysis products of sinigrin may exert a potentially toxic effect on the myocardial tissue of female mice and possess the capability to modulate transcription factors in vivo in a sex-dependent manner. This observation calls for further investigation into the mechanisms regulating the actions of glucosinolate hydrolysis products, their interactions with sex hormones, and the determination of permissible intake levels associated with both beneficial and adverse outcomes.

Ancestral Nitrilase Mining and Semi-Rational Engineering for Enhanced Thermal Stability in Rapeseed Meals-Derived Nitriles Degradation

Rapeseed meal (RSM), a protein-rich byproduct, holds potential as a high-quality animal feed, but nitrile compounds derived from glucosinolates (GSLs) in RSM pose a toxicity risk. Nitrilases, enzymes that hydrolyze toxic nitriles to carboxylic acids, offer a potential solution for detoxification. However, the low thermal stability of nitrilases restricts their industrial applicability. We herein identified eight ancestral nitrilases through sequence-based mining using 6803NIT as a probe enzyme. Among these, ancestral enzyme A1 exhibited the highest specific activity (58.3 U/mg) and half-life (t1/2 = 3.5 h at 40 °C). To enhance thermal stability, we engineered a quadruple mutant A1M_4C, which exhibited a 4.7-fold increase in half-life (t1/2 = 16.3 h) and a 2-fold increase in specific activity (118.5 U/mg). Kinetic analysis revealed a reduction in Km from 14.9 to 10.5 mM and an increase in kcat/Km from 1.9 to 4.37 s-1·mM-1. Mechanistic studies indicated that enhanced stability in A1M_4C was due to increased hydrogen bonding and stronger amino acid interactions. Simulated feed pelletization at 90 °C for 2 min showed that A1M_4C acquired a 22.2-fold improvement toward nitriles degradation over wild-type A1. These findings demonstrate the potential of ancestral enzyme mining to develop thermostable nitrilases for industrial feed applications.

Nitrilase GiNIT from Gibberella intermedia Efficiently Degrades Nitriles Derived from Rapeseed Meal Glucosinolate

Rapeseed meal is severely restricted in its utilization as unconventional animal feed due to anti-nutritive compounds, such as glucosinolate, that are degraded to toxic nitriles such as 3-butenenitrile and 4-pentenenitrile in animals. Few studies on nitrilases that can degrade glucosinolate-derived nitriles have been reported thus far. In the present study, a nitrilase gene GiNIT from Gibberella intermedia was over-expressed in Escherichia coli and the purified recombinant nitrilase rGiNIT showed specific activities of 134.48 U/mg and 122.16 U/mg when using 3-butenenitrile and 4-pentenenitrile as substrates at the optimal pH, 7.5, and temperature, 45 °C, which is the highest reported in the literature. The conversion of 3-butenenitrile and 4-pentenenitrile by rGiNIT reached 81.89% and 80.23% after hydrolysis for 15 min and 300 min, respectively. Site-directed mutagenesis and molecular docking analysis revealed that the catalytic ability of rGiNIT depended on the substrate binding pocket comprising 13 key amino acid residues. These results provide a potential enzyme resource for rapeseed meal detoxification and theoretical guidance for protein engineering.

Molecular Modification Strategies of Nitrilase for Its Potential Application in Agriculture

Some feed source plants will produce secondary metabolites such as cyanogenic glycosides during metabolism, which will produce some poisonous nitrile compounds after hydrolysis and remain in plant tissues. The consumption of feed-source plants without proper treatment affect the health of the animals' bodies. Nitrilases can convert nitriles and have been used in industry as green biocatalysts. However, due to their bottleneck problems, their application in agriculture is still facing challenges. Acid-resistant nitrilase preparations, high-temperature resistance, antiprotease activity, strong activity, and strict reaction specificity urgently need to be developed. In this paper, the application potential of nitrilase in agriculture, especially in feed processing industry was explored, the source properties and catalytic mechanism of nitrilase were reviewed, and modification strategies for nitrilase application in agriculture were proposed to provide references for future research and application of nitrilase in agricultural and especially in the biological feed scene.

Maximizing the potential of nitrilase: Unveiling their diversity, catalytic proficiency, and versatile applications

Nitrilases represent a distinct class of enzymes that play a pivotal role in catalyzing the hydrolysis of nitrile compounds, leading to the formation of corresponding carboxylic acids. These enzymatic entities have garnered significant attention across a spectrum of industries, encompassing pharmaceuticals, agrochemicals, and fine chemicals. Moreover, their significance has been accentuated by mounting environmental pressures, propelling them into the forefront of biodegradation and bioremediation endeavors. Nevertheless, the natural nitrilases exhibit intrinsic limitations such as low thermal stability, narrow substrate selectivity, and inadaptability to varying environmental conditions. In the past decade, substantial efforts have been made in elucidating the structural underpinnings and catalytic mechanisms of nitrilase, providing basis for engineering of nitrilases. Significant breakthroughs have been made in the regulation of nitrilases with ideal catalytic properties and application of the enzymes for industrial productions. This review endeavors to provide a comprehensive discourse and summary of recent research advancements related to nitrilases, with a particular emphasis on the elucidation of the structural attributes, catalytic mechanisms, catalytic characteristics, and strategies for improving catalytic performance of nitrilases. Moreover, the exploration extends to the domain of process engineering and the multifarious applications of nitrilases. Furthermore, the future development trend of nitrilases is prospected, providing important guidance for research and application in the related fields.

Biotransformation technology and high-value application of rapeseed meal: a review

Rapeseed meal (RSM) is an agro-industrial residue of increased functional biological value that contains high-quality proteins for animal feed. Due to the presence of antinutritional factors and immature development technology, RSM is currently used as a limited feed additive and in other relatively low-value applications. With increasing emphasis on green and sustainable industrial development and the added value of agro-industrial residues, considerable attention has been directed to the removal of antinutritional factors from RSM using high-efficiency, environment-friendly, and cost-effective biotechnology. Similarly, the high-value biotransformations of RSM have been the focus of research programmes to improve utilization rate. In this review, we introduce the sources, the nutrient and antinutrient content of RSM, and emphasize improvements on RSM feed quality using biological methods and its biotransformation applications.