A Multienzyme Cascade Pathway Immobilized in a Hydrogen-Bonded Organic Framework for the Conversion of CO2

The reduction of carbon dioxide to valuable chemicals through enzymatic processes is regarded as a promising approach for the reduction of carbon dioxide emissions. In this study, an in vitro multi-enzyme cascade pathway is constructed for the conversion of CO2 into dihydroxyacetone (DHA). This pathway, known as FFFP, comprises formate dehydrogenase (FDH), formaldehyde dehydrogenase (FaldDH), formolase (FLS), and phosphite dehydrogenase (PTDH), with PTDH serving as the critical catalyst for regenerating the coenzyme NADH. Subsequently, the immobilization of the FFFP pathway within the hydrogen-bonded organic framework (HOF-101) is accomplished in situ. A 1.8-fold increase in DHA yield is observed in FFFP@HOF-101 compared to the free FFFP pathway. This enhancement can be explained by the fact that within FFFP@HOF-101, enzymes are positioned sufficiently close to one another, leading to the elevation of the local concentration of intermediates and an improvement in mass transfer efficiency. Moreover, FFFP@HOF-101 displays a high degree of stability. In addition to the establishment of an effective DHA production method, innovative concepts for the tailored synthesis of fine compounds from CO2 through the utilization of various multi-enzyme cascade developments are generated by this work.

Effects of Different Doses of Multienzyme Supplementation on Growth Performance, Duodenal pH and Morphology, and Carcass Traits in Broilers Fed Diets with an Increasing Reduction in Energy

This study evaluated the effects of supplementing different doses of a multienzyme (KZP) consisting of carbohydrases and a protease on growth performance, duodenal pH and morphology, and carcass traits in broilers fed diets with increasing reductions in energy. One thousand two hundred one-day-old broiler chicks were allocated to five dietary treatments with eight replicates of 30 birds each: a positive control diet formulated to meet Arbor Acres' nutritional requirements (PC); a negative control diet reformulated to 80 kcal/kg less than the apparent metabolizable energy (AME) of the PC (NC1); a negative control diet reformulated to 120 kcal/kg less than the AME of the PC (NC2); an NC1 diet supplemented with 300 g/t of KZP (NC1 + KZP300); and an NC2 supplemented with 500 g/t of KZP (NC2 + KZP500). Growth performance was measured throughout the study. At 35 days, 10 birds per treatment were randomly selected and euthanized for a carcass trait evaluation, and samples of the duodenum were collected for morphological examination and pH level determination. The final average body weight and feed conversion ratio were better (p < 0.05) for the broilers in the NC1 + KZP300 group compared to those in NC1, NC2 and NC2 + KZP500 groups and were similar to those of the PC birds (p > 0.05). Birds from the NC1 + KZP500 group showed a better (p < 0.05) final body weight and feed efficiency compared to the NC1 and NC2 groups. The villus height was greater (p < 0.05) for the PC and NC1 + KZP300 groups compared to the rest of the treatments. The crypt depth was longer (p < 0.05) for the NC1 and NC2 groups compared to the NC1 + KZP300 group. The supplementation of KZP to both the NC1 and NC2 diets reduced (p < 0.05) the abdominal fat %. This study demonstrates that supplementing energy-reduced diets with KZP improved performance in broiler chickens.

Evaluation of multienzyme supplementation and fiber levels on nutrient and energy digestibility of diets fed to gestating sows and growing pigs

The objective was to investigate the effect of a multienzyme blend (MEblend) and inclusion level on apparent total tract digestibility (ATTD) of energy and nutrients, as well as ileal digestibility of crude protein (CP) and amino acids (AA) in gestation diets with low (LF) or high-dietary fiber (HF) fed to gestation sows. For comparison, growing pigs were fed the same HF diets to directly compare ATTD values with the gestating sows. In experiment 1, 45 gestating sows (parity 0 to 5; 187 ± 28 kg bodyweight; BW) were blocked by parity in a 2 × 3 factorial arrangement and fed 2.2 kg/d of the HF (17.5% neutral detergent fiber; NDF) or LF (13% NDF) diet and one of three levels of MEblend (0.0%, 0.08%, and 0.1%) to determine impacts of MEblend on ATTD. Twenty-seven growing pigs (initial 35.7 ± 3.32 kg BW) were fed the same HF diet (5% of BW) and one of three MEblend inclusions. The MEblend at both 0.08% and 0.1% increased ATTD of energy, NDF, and acid detergent fiber (ADF) (P < 0.05) in gestating sows but ATTD of total non-starch polysaccharides (NSP) and its residues were not affected. Sows fed HF, regardless of MEblend, had greater ATTD of NDF, xylose, and total NSP (P < 0.05) in comparison to grower pigs. In experiment 2, ileal cannulas were placed in 12 gestating sows (parity 0 to 2; BW 159 ± 12 kg) to determine apparent and standardized ileal digestibility (AID and SID) of AA and NSP. In a crossover design, sows were fed the same six diets, as in experiment 1, and a nitrogen-free diet during five periods of seven days each to achieve eight replicates per diet. There was no interaction between diet fiber level and MEblend inclusion. Supplementation of MEblend to gestating sow diets did not impact SID of CP and AA regardless of dietary fiber level. The SID of His, Ile, Lys, Phe, Thr, Trp, and Val were 3% to 6% lower (P < 0.09) in HF than LF independent of MEblend. Supplementation of MEblend did not impact AID of NSP components, but sows fed HF had higher AID of arabinose (LF: 26.5% vs. HF: 40.6%), xylose (LF: 3.5% vs. HF: 40.9%), and total NSP (LF: 25.9% vs. HF: 40.0%) compared to sows fed LF (P < 0.05). Dietary supplementation of MEblend increased ATTD of nutrients, NSP, and energy in diets fed to gestating sows regardless of inclusion level, with MEblend having a greater incremental increase in diets with lower NDF levels. Inclusion of MEblend impacted neither SID of AA nor AID of NSP in low- or high-fiber gestation diets, but high-fiber diet, negatively affected SID of AA.

Effects of Using Processed Amaranth Grain with and without Enzyme on Performance, Egg Quality, Antioxidant Status and Lipid Profile of Blood and Yolk Cholesterol in Laying Hens

The objective of this study was to investigate the effects of feeding Amaranthus hybridus chlorostachys grain (AG) with (+E) and without enzyme (−E) on performance, egg quality, antioxidant status and lipid profile of blood serum and yolk cholesterol in laying hens. A total of 960 white leghorn (Hy-line W-36) commercial layers (56 weeks) were divided into 10 groups with 8 replicates per group (12 birds per replicate, including 3 adjacent cages with 4 birds each). A completely randomized design was implemented with a 5 × 2 factorial arrangement of treatments consisting of five levels of AG (0, 100, 200, 300 and 400 g/kg) and two levels of multienzyme complex addition (0 −E and 0.25 +E g/kg) fed to the hens for 12 weeks (2 wk. adaptation + 10 wk. main experiment). Feed intake (FI) and percentage of hen day production (HDP) were not affected by main effect of the AG level, but egg mass (EM) and egg weight (EW) were decreased (p < 0.01), and the feed conversion ratio (FCR) was impaired (p < 0.01). EM, EW and FCR were improved by enzyme addition (p < 0.01). EM, EW and FCR were affected (p < 0.01) by the interaction of AG and enzyme addition. The highest value of EM and the lowest value of FCR were observed in hens on the diet containing 200 g/kg AG with enzyme addition. Egg yolk cholesterol content was reduced (p < 0.05) by up to 10% with increasing levels AG in experimental diets. The egg quality traits, including Haugh units of protein quality, strength and shell thickness, were not affected by the main effects or interaction of AG and enzyme consumption. Amaranth feeding led to a decrease (p < 0.05) in triglyceride (TG) and low-density lipoprotein (LDL) while also promoting increases (p < 0.05) in the high-density lipoprotein (HDL) and total antioxidant capacity (TAC) of the blood. A comparison of the effects of contrasts showed that functional parameters (except FI), yolk cholesterol, antioxidant parameters (except MDA) and blood lipid profile had differed significantly (p < 0.05) between the hens fed amaranth versus those not fed amaranth. These findings indicate that feeding a diet containing up to 200 g/kg of AG with enzyme addition can improve EW, EM and FCR. Feeding laying hens diets containing AG also positively influenced blood traits and antioxidant status in laying hens while reducing egg yolk cholesterol content.

Hierarchically Porous Biocatalytic MOF Microreactor as a Versatile Platform towards Enhanced Multienzyme and Cofactor-Dependent Biocatalysis

Metal-organic frameworks (MOFs) have recently emerged as excellent hosting matrices for enzyme immobilization, offering superior physical and chemical protection for biocatalytic reactions. However, for multienzyme and cofactor-dependent biocatalysis, the subtle orchestration of enzymes and cofactors is largely disrupted upon immobilizing in the rigid crystalline MOF network, which leads to a much reduced biocatalytic efficiency. Herein, we constructed hierarchically porous MOFs by controlled structural etching to enhance multienzyme and cofactor-dependent enzyme biocatalysis. The expanded size of the pores can provide sufficient space for accommodated enzymes to reorientate and spread within MOFs in their lower surface energy state as well as to decrease the inherent barriers to accelerate the diffusion rate of reactants and intermediates. Moreover, the developed hierarchically porous MOFs demonstrated outstanding tolerance to inhospitable surroundings and recyclability.

Type I fatty acid synthase trapped in the octanoyl-bound state

De novo fatty acid biosynthesis in humans is accomplished by a multidomain protein, the Type I fatty acid synthase (FAS). Although ubiquitously expressed in all tissues, fatty acid synthesis is not essential in normal healthy cells due to sufficient supply with fatty acids by the diet. However, FAS is overexpressed in cancer cells and correlates with tumor malignancy, which makes FAS an attractive selective therapeutic target in tumorigenesis. Herein, we present a crystal structure of the condensing part of murine FAS, highly homologous to human FAS, with octanoyl moieties covalently bound to the transferase (MAT—malonyl‐/acetyltransferase) and the condensation (KS—β‐ketoacyl synthase) domain. The MAT domain binds the octanoyl moiety in a novel (unique) conformation, which reflects the pronounced conformational dynamics of the substrate‐binding site responsible for the MAT substrate promiscuity. In contrast, the KS binding pocket just subtly adapts to the octanoyl moiety upon substrate binding. Besides the rigid domain structure, we found a positive cooperative effect in the substrate binding of the KS domain by a comprehensive enzyme kinetic study. These structural and mechanistic findings contribute significantly to our understanding of the mode of action of FAS and may guide future rational inhibitor designs.

Growth performance and nutrient digestibility of growing and finishing pigs fed multienzyme-supplemented low-energy and -amino acid diets

A study was conducted to determine the effects of supplementing corn-soybean meal-based diets with a multienzyme on growth performance, bone mineralization, apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of nutrients of growing pigs. A total of 276 pigs (body weight [BW] = 33.99 ± 4.3 kg) were housed by sex in 45 pens of 6 or 7 pigs and fed 5 diets (9 pens/diet) in a randomized complete block design. Diets were positive control (PC); and negative control 1 (NC1) or negative control 2 (NC2) without or with multienzyme. The multienzyme used supplied at least 1,800, 1,244, 6,600, and 1,000 units of xylanase, β-glucanase, arabinofuranosidase, and phytase per kilogram of diet, respectively. The PC diet was adequate in all nutrients according to NRC recommendations and had greater digestible P content than NC1 or NC2 diet by 0.134 percentage points. The PC diet had greater net energy (NE) and standardized ileal digestible amino acids (AA) content than NC1 diet by 3%, and than NC2 diet by 5%. The diets were fed in 4 phases based on BW: Phase 1: 34-50 kg; Phase 2: 50-75 kg; Phase 3: 75-100 kg; and Phase 4: 100-120 kg. Nutrient digestibility and bone mineralization were determined at the end of Phase 1. Overall (34-120 kg BW), pigs fed the PC and NC1 diets did not differ in average daily gain (ADG) and average daily feed intake. Pigs fed NC2 diet had lower (P < 0.05) ADG and gain-to-feed ratio (G:F) than those fed PC diet. Pigs fed PC diet had greater (P < 0.05) bone ash content and ATTD of P than those fed NC1 diet. The ATTD of GE for PC diet was greater (P < 0.05) than that for NC2 diet, and tended to be greater (P < 0.10) than that for NC1 diet. Multienzyme interacted (P < 0.05) with negative control diet type on overall ADG and AID of GE such that multienzyme did not affect overall ADG and AID of GE for the NC1 diet, but increased (P < 0.05) overall ADG and AID of GE for NC2 diet by 5.09 and 8.74%, respectively. Multienzyme did not interact with negative control diet type on overall G:F, bone ash content, AID of AA, and ATTD of nutrients. Multienzyme increased (P < 0.05) overall G:F, AID of methionine, ATTD of GE and P, and tended to increase (P = 0.056) bone ash content. The ADG, bone ash content, and ATTD of GE and P for the multienzyme-supplemented diets were similar to (P > 0.10) PC diet. Thus, NE and digestible AA and P can be lowered by ≤5% in multienzyme-supplemented diets without effects on growth performance and bone ash of pigs.

Growth, carcass characteristics, and meat quality of broilers fed a low-energy diet supplemented with a multienzyme preparation

The effect of a low-ME diet with a multienzyme (Kemzyme Plus, Kemin, Des Moines, IA) blend on performance, meat quality, and carcass traits was evaluated in Hubbard broiler chicks. A total of 120 Hubbard broiler chicks were allocated to the following 4 experimental groups and every group was separated into 6 replicates, with 5 birds per replicate: control (3,180 kcal/kg of ME), control + 0.50 g/kg diet of enzyme (Cont-Enz), low-ME diet (3,080 kcal/kg), and low-ME + 0.50 g/kg diet of enzyme (low-ME-Enz). The trail lasted for 16 D (32 to 48 D of age). No significant differences in growth parameters or carcass traits were observed among treatments. However, liver weight increased with the low-ME-Enz diet (P = 0.038). The low-ME diet recorded the highest weight for the bursa (P = 0.043) and thymus (P = 0.019). Dietary treatments had significant impacts on the length of duodenum, ileum, and cecum, as well as the weight of duodenum. The length of duodenum, ileum, and cecum increased with enzyme supplementation. The myofibril fragmentation index was lower with the Cont-Enz, low-ME, and low-ME-Enz diets than with the control diet (P = 0.043). The shear force increased with the low-ME-Enz diet (P = 0.022) than the control diet. Dietary treatments influenced breast meat yellowness (P = 0.019), whereas the low-ME diet had the lowest yellowness at the slaughtering age. The dietary treatments affected the breast meat pH (P = 0.001), with the control diet having the highest pH value after 24 hours. Thus, there was no effect of low-ME or enzyme supplementation to the control or low-ME diet on growth performance or carcass yield. However, feeding a low-ME diet or Cont-Enz preparation influenced organ and small intestine weights and meat characteristics.

Multienzyme immobilized polymeric membrane reactor for transformation of lignin model compound

We have developed a multienzyme functionalized membrane reactor for bioconversion of lignin model compound involving enzymatic catalysis. Layer-by-layer approach was used to immobilize three different enzymes (glucose oxidase, peroxidase and laccase) into pH-responsive membranes. This novel membrane reactor couples the in situ generation of hydrogen peroxide (by glucose oxidase) to oxidative conversion of a lignin model compound, guaiacylglycerol-B-guaiacylether (GGE). Preliminary investigation of the efficacy of these functional membranes towards GGE degradation is demonstrated under convective flow mode. Over 90% of the initial feed could be degraded with the multienzyme immobilized membranes at a residence time of approximately 22 seconds. GGE conversion product analysis revealed formation of oligomeric oxidation products with peroxidase, which might be potential hazard to membrane bioreactors. These oxidation products could be further degraded by laccase enzymes in the multienzymatic membranes explaining the potential of multienzyme membrane reactors. The multienzyme incorporated membrane reactors were active for about a month time of storage at 4 °C, and retention of activity was demonstrated after repetitive use.

High-Speed Atomic Force Microscopy Visualization of the Dynamics of the Multienzyme Fatty Acid Synthase

Multienzymes, such as the protein metazoan fatty acid synthase (FAS), are giant and highly dynamic molecular machines for critical biosynthetic processes. The molecular architecture of FAS was elucidated by static high-resolution crystallographic analysis, while electron microscopy revealed large-scale conformational variability in FAS with some correlation to functional states in catalysis. However, little is known about time scales of conformational dynamics, the trajectory of motions in individual FAS molecules, and the extent of coupling between catalysis and structural changes. Here, we present an experimental single-molecule approach to film immobilized or selectively tethered FAS in solution at different viewing angles and high spatiotemporal resolution using high-speed atomic force microscopy. Mobility of individual regions of the multienzyme is recognized in video sequences, and correlation of shape features implies a convergence of temporal resolution and velocity of FAS dynamics. Conformational variety can be identified and grouped by reference-free 2D class averaging, enabling the tracking of conformational transitions in movies. The approach presented here is suited for comprehensive studies of the dynamics of FAS and other multienzymes in aqueous solution at the single-molecule level.

In Vivo Multienzyme Complex Coconstruction of N-Acetylneuraminic Acid Lyase and N-Acetylglucosamine-2-epimerase for Biosynthesis of N-Acetylneuraminic Acid

Metabolic channeling enables efficient transfer of the intermediates by forming a multienzyme complex. To leverage the metabolic channeling for improved biosynthesis, we coexpressed N-acetylneuraminic acid lyase from C. glutamicum ATCC 13032 (CgNal) and N-acetylglucosamine-2-epimerase from Anabaena sp. CH1 (anAGE) in Escherichia coli and used the whole cell to synthesize N-acetylneuraminic acid (Neu5Ac) from N-acetylglucosamine (GlcNAc) and pyruvate. To get the multienzyme complex, polycistronic plasmid with high levels of CgNal and anAGE expression was constructed by tuning the orders of the genes. The Shine-Dalgarno (SD) sequence and aligned spacing (AS) distance were optimized. The E. coli Rosetta harboring the polycistronic plasmid pET-28a-SD₂-AS₁-CgNal-SD-AS-anAGE increased the production of Neu5Ac by 58.7% to 92.5 g/L in 36 h by whole-cell catalysis and by 21.9% up to 112.8 g/L in 24 h with the addition of Triton X-100.

Crystallization and X-ray diffraction studies of a complete bacterial fatty-acid synthase type I

Bacterial and fungal type I fatty-acid synthases (FAS I) are evolutionarily connected, as bacterial FAS I is considered to be the ancestor of fungal FAS I. In this work, the production, crystallization and X-ray diffraction data analysis of a bacterial FAS I are reported.

While a deep understanding of the fungal and mammalian multi-enzyme type I fatty-acid synthases (FAS I) has been achieved in recent years, the bacterial FAS I family, which is narrowly distributed within the Actinomycetales genera Mycobacterium, Corynebacterium and Nocardia, is still poorly understood. This is of particular relevance for two reasons: (i) although homologous to fungal FAS I, cryo-electron microscopic studies have shown that bacterial FAS I has unique structural and functional properties, and (ii) M. tuberculosis FAS I is a drug target for the therapeutic treatment of tuberculosis (TB) and therefore is of extraordinary importance as a drug target. Crystals of FAS I from C. efficiens, a homologue of M. tuberculosis FAS I, were produced and diffracted X-rays to about 4.5 Å resolution.