Biofilms are structured communities of bacteria encased in a self-produced matrix of proteins, extracellular DNA, and polysaccharides. Within these fortresses, pathogens become dramatically more tolerant of antibiotics and immune attack, which is why biofilms complicate the treatment of cystic fibrosis lungs, chronic wounds, medical implants, and catheter-associated infections. Pseudomonas aeruginosa and Staphylococcus aureus are flagship biofilm builders, and both appear on global lists of antibiotic-resistant priority pathogens. An enzyme that can chew through the proteinaceous scaffolding of a biofilm, or disrupt the physiology of the cells inside it, therefore represents a genuinely different therapeutic strategy: rather than killing bacteria outright, it dismantles the architecture that makes them so hard to eradicate.

Serratiopeptidase, sometimes marketed as serrapeptase, is an extracellular protease naturally secreted by Serratia marcescens. It has been used for decades, particularly in Japan and India, as an anti-inflammatory and anti-edema agent, and earlier studies have hinted that it can affect Pseudomonas physiology and biofilm integrity. What has been missing is a rigorous, quantitative characterization of a purified preparation, since crude enzyme mixtures make it impossible to attribute activity to a single protein. The new study addressed this gap with a four-step purification pipeline: precipitation, dialysis, ion-exchange chromatography, and gel filtration chromatography, which together yielded a 15.91-fold increase in purity, sufficient for reliable biochemical and kinetic analysis.

With the purified enzyme in hand, the team determined its molecular weight to be approximately 47 kilodaltons, consistent with the serralysin-like metalloproteases produced by Serratia species. The enzyme displayed broad substrate specificity but showed its highest affinity toward casein, a milk protein commonly used as a benchmark substrate in protease assays. Activity peaked at pH 7 and 40 degrees Celsius, close to physiological conditions, and the enzyme proved remarkably durable under these optima, retaining 89.2 percent and 82.4 percent of its activity, respectively, after 60 minutes of incubation. That combination of neutral pH preference and moderate temperature optimum is exactly what one would want in a therapeutic protein intended to function inside the human body.

The kinetic analysis revealed an enzyme of impressive catalytic power. The Michaelis constant, Km, was 0.034 millimolar, equivalent to 842 micrograms per milliliter, indicating tight substrate binding, while the maximum velocity, Vmax, reached 738.2 units per milliliter. The turnover number, kcat, came in at 55.3 per second, meaning each enzyme molecule processes more than 55 substrate molecules every second. Dividing kcat by Km yields a catalytic efficiency of 1.64 × 10⁶ per molar per second, a figure that places this serratiopeptidase firmly in the category of highly efficient catalysts. For a protein being considered as a drug candidate, such numbers matter: an efficient enzyme can deliver biological effects at lower doses, reducing cost and potential side effects.

Equally informative was the enzyme’s response to chemical modulators. Metal ions including zinc, cobalt, barium, and manganese enhanced activity, as did the non-ionic detergent Tween-20 and the reducing agent beta-mercaptoethanol. Conversely, EDTA, a chelator that strips away metal cofactors, and PMSF, a classic serine protease inhibitor, both shut the enzyme down. This dual sensitivity is diagnostic: it confirms that the SP6 enzyme is a serine-metalloprotease, a hybrid classification consistent with the serralysin family, in which a catalytic serine operates within a metal-dependent active site. Knowing this helps predict how the enzyme will behave in complex biological environments and informs strategies for stabilizing it in formulation.

Perhaps the most clinically relevant findings concern stability and resistance to degradation. The enzyme retained 61.31 percent of its activity after 60 days of storage at 4 degrees Celsius, a refrigerated shelf life that simplifies handling and distribution. More strikingly, it resisted digestion by trypsin and by human serum, with in vitro half-lives of 4 and 5 hours, respectively. Therapeutic proteins typically face rapid destruction by circulating proteases and serum components, so a bacterial enzyme that survives hours in serum-like conditions is unusual and valuable. The authors note that extending the half-lives of therapeutic proteins is a major focus of drug development, and intrinsic resistance to proteolysis gives this enzyme a head start.

The anti-biofilm experiments delivered the study’s headline result. Against Pseudomonas aeruginosa MTCC 2453, serratiopeptidase achieved a maximum biofilm inhibition of 41.65 percent at a concentration of 200 micrograms per milliliter, with an IC50 of 56.92 plus or minus 8 micrograms per milliliter. Against Staphylococcus aureus MTCC 1430, the maximum inhibition was 21.87 percent at the same dose, with an IC50 of 124.6 plus or minus 8 micrograms per milliliter. The authors are careful to define these IC50 values relative to the normalized response range, meaning they correspond to 50 percent of the observed inhibitory effect rather than absolute halving of biofilm mass, a methodological honesty that strengthens the credibility of the data. The stronger effect against Pseudomonas aligns with earlier reports that serratiopeptidase alters the physiology of Pseudomonas isolates from cystic fibrosis patients and disrupts Pseudomonas biofilms and functional amyloids.

What makes these numbers exciting is not that the enzyme obliterates biofilms on its own, but that partial disruption is often enough to restore the vulnerability of embedded bacteria. Anti-biofilm agents are increasingly viewed as adjuncts: by loosening or thinning the matrix, they allow antibiotics and immune cells to reach cells that would otherwise remain sheltered. A 41.65 percent reduction in Pseudomonas biofilm formation, achieved by a single enzyme at a modest concentration, could meaningfully amplify the efficacy of co-administered antimicrobials. The enzyme’s activity at neutral pH and 40 degrees Celsius, its serum stability, and its resistance to trypsin all support the plausibility of such combination approaches.

Significant hurdles remain before serratiopeptidase reaches the clinic as an anti-biofilm drug. The current work used a partially purified preparation, and further purification, scale-up of production, formulation studies, toxicity testing, and ultimately animal and clinical trials will be required. The enzyme’s origin from Serratia marcescens, an opportunistic pathogen itself, raises production and safety questions that recombinant expression systems, which have already been used to produce serratiopeptidase in cell-free platforms, could help resolve. Nevertheless, by systematically documenting the enzyme’s molecular weight, kinetics, inhibitor profile, storage stability, serum resistance, and anti-biofilm potency, Kumar and Bhattacharya have transformed a supplement-shelf enzyme into a well-characterized candidate for rational development. As antibiotic resistance continues to erode the effectiveness of conventional drugs, enzymes that dismantle bacterial fortresses rather than merely poisoning the bacteria inside them may prove to be one of the most important weapons in the next generation of anti-infective therapy.

Subject of Research: Biochemical characterization and anti-biofilm activity of serratiopeptidase from Serratia marcescens SP6

Article Title: Elucidation of the biochemical properties of a partially purified Serratia marcescens SP6 serratiopeptidase with anti-biofilm efficacy

Article References: Kumar, S., & Bhattacharya, S. (2026). Elucidation of the biochemical properties of a partially purified Serratia marcescens SP6 serratiopeptidase with anti-biofilm efficacy. 3 Biotech, 16(10), Article 433. https://doi.org/10.1007/s13205-026-05063-9

Image Credits: AI Generated

DOI: 10.1007/s13205-026-05063-9

Keywords: serratiopeptidase, Serratia marcescens, biofilm, Pseudomonas aeruginosa, Staphylococcus aureus, protease, enzyme kinetics, antibiotic resistance, metalloprotease, anti-biofilm therapy, protein purification, therapeutic enzymes

Cinnamyl acetate, an ester that carries warm, balsamic, cinnamon-like notes, is a defining contributor to the aroma bouquet of P. mume flowers. While previous work had traced parts of the scent pathway, including the production of cinnamyl alcohol by the enzyme PmCAD1 and the role of benzyl alcohol acetyltransferase genes in other scent compounds, the gene responsible for the final acetylation step that converts cinnamyl alcohol into cinnamyl acetate had never been pinpointed. The new study set out to find it by systematically mining the plant’s genome.

The researchers began with a genome-wide survey of the variety P. mume var. tortuosa, identifying 116 members of the acyltransferase gene family, a large group of enzymes known to attach acyl groups to alcohols and other acceptor molecules. Because floral scent genes typically show activity patterns that mirror the accumulation of their volatile products, the team then cross-referenced transcriptome data from different cultivars with reverse-transcription quantitative PCR measurements taken from petals at four distinct flowering developmental stages. This screening strategy narrowed the field to three candidate cinnamyl alcohol acyltransferase genes, which the researchers named PmCAAT1, PmCAAT2, and PmCAAT3.

Sequence analysis of the three cloned genes revealed that their protein products carry the hallmarks of the BAHD acyltransferase superfamily, a widespread class of plant enzymes named after its first characterized members. In particular, all three proteins contain the conserved HXXXD catalytic motif, which positions a key histidine residue for the transfer reaction, and the DFGWG motif that forms part of the substrate-binding pocket. These motifs are the structural fingerprints that biochemists use to recognize enzymes that shuttle activated acyl groups, typically from acetyl-coenzyme A, onto alcohol substrates to form esters.

Evolutionary comparisons added an important layer of insight. Phylogenetic analysis showed that PmCAAT1 sits closest to the clade of coniferyl alcohol acetyltransferases, enzymes previously implicated in phenylpropanoid volatile production, whereas PmCAAT2 and PmCAAT3 clustered together on a separate evolutionary branch. This split hinted that the three paralogs, despite their shared ancestry, may have diverged in function, a hypothesis the team put to the test using both cellular and biochemical assays.

Subcellular localization experiments showed that all three proteins reside in the nucleus and the cytoplasm. This dual distribution is notable because acyltransferases have increasingly been recognized as enzymes that can moonlight in the nucleus, and the localization pattern suggests the enzymes may encounter their substrates in multiple cellular compartments. To assess their roles in living tissue, the researchers used transient expression in P. mume petals, demonstrating that all three genes could regulate the biosynthesis of cinnamyl acetate when expressed in the flower tissue itself.

The decisive evidence came from the biochemistry. Using prokaryotic expression systems to produce the enzymes and in vitro activity assays to test them, the team confirmed that PmCAAT1 and PmCAAT2 can both catalyze the conversion of cinnamyl alcohol to cinnamyl acetate, while PmCAAT3 did not show this activity. Enzyme kinetics then revealed a crucial difference between the two active enzymes: although both display broad substrate selectivity, PmCAAT1 exhibits a strong preference for cinnamyl alcohol, making it the most likely primary driver of cinnamyl acetate production in the flowers. PmCAAT2, by contrast, accepts a wider range of substrates, including the monoterpene linalool, suggesting it may contribute to multiple scent compounds.

The findings place P. mume within a growing body of work showing how plants fine-tune their volatile profiles through the evolution of specialized acyltransferases. Comparable enzymes have been shown to shape the ester aromas of strawberry, banana, melon, rose, grape, and peach, where differences in enzyme activity and substrate preference translate directly into differences in flavor and fragrance. In peach, for example, variation in the activity of a single alcohol acyltransferase explains why high-aroma varieties produce far more of the lactone volatiles prized by consumers. The P. mume study extends this paradigm to ornamental floral scent and to the phenylpropanoid pathway in particular.

Beyond its fundamental interest, the work carries practical weight for horticulture. Because the fragrance of P. mume is a major part of its ornamental and cultural value, knowing which gene supplies the key ester gives breeders a molecular handle for selecting or engineering plants with enhanced aroma. The authors suggest that the results provide a theoretical foundation for molecular breeding of floral fragrance in the species, potentially allowing marker-assisted selection for high PmCAAT1 activity or the use of genome editing to boost scent output. Understanding the enzyme’s substrate preference may also guide metabolic engineering efforts aimed at producing cinnamyl acetate biotechnologically.

The study, led by corresponding author Tengxun Zhang with co-first authors Jinhong Li and Jialu Guan, was supported by the National Natural Science Foundation of China and benefited from gas chromatography time-of-flight mass spectrometry support for volatile detection. As genome resources for ornamental plants continue to expand, enzyme-by-enzyme dissections of scent pathways like this one are transforming fragrance from a subjective trait into a set of manipulable biochemical reactions, promising gardens and orchards where the aromas of spring can be designed as deliberately as their colors.

Subject of Research: Biosynthesis of the floral volatile cinnamyl acetate by cinnamyl alcohol acyltransferases in Prunus mume

Article Title: Cinnamyl alcohol acyltransferase PmCAAT1 specifically catalyzes the formation of the characteristic volatile cinnamyl acetate of Prunus mume

Article References: Li, J., Guan, J., Zhang, S., Lei, M., Li, J., Zhang, Y., & Zhang, T. (2026). Cinnamyl alcohol acyltransferase PmCAAT1 specifically catalyzes the formation of the characteristic volatile cinnamyl acetate of Prunus mume. Plant Cell Reports, 45(10), Article 306. https://doi.org/10.1007/s00299-026-03992-6

Image Credits: AI Generated

DOI: 10.1007/s00299-026-03992-6

Keywords: Prunus mume, cinnamyl acetate, PmCAAT1, BAHD acyltransferase, floral scent, volatile organic compounds, phenylpropanoid pathway, enzyme kinetics, plant biochemistry, molecular breeding, ornamental horticulture, Plant Cell Reports

Lipases are the enzymes responsible for breaking down dietary triglycerides into absorbable fatty acids and monoacylglycerides. Because of this central role in fat digestion, they have long been recognised as prime therapeutic targets for obesity and related metabolic disorders. The best-known anti-obesity drug on the market, orlistat, works precisely by inhibiting pancreatic lipase in the gut, preventing a portion of dietary fat from ever entering the bloodstream. However, screening new lipase inhibitors requires a dependable enzyme model that behaves predictably, is easy to produce and accurately reflects the biology of human digestive lipases. Lipase ITB 2.1, originally isolated from an Indonesian hot spring bacterium, may now fill that role.

The team began with a deep evolutionary dive into lipase sequences drawn from bacterial, fungal and mammalian sources. Multiple sequence alignment revealed that the catalytic serine residue, which sits at the so-called nucleophilic elbow of the enzyme and performs the decisive chemical step of fat cleavage, is strongly conserved across all three domains of life. This conservation is the molecular linchpin that makes a bacterial enzyme a meaningful proxy for its human counterparts. Interestingly, the analysis also uncovered rare substitutions in the canonical pentapeptide motif surrounding the catalytic serine. While most lipases carry the characteristic GXSXG motif, certain Bacillus and Geobacillus species display AXSXG variants, hinting at adaptive structural variation among thermostable bacterial enzymes.

Phylogenetic and distance-based analyses then mapped out the evolutionary relationships among these enzymes. The resulting trees showed clear clustering by lineage, yet they also revealed unexpected overlaps between mammalian, fungal and bacterial lipases that the authors interpret as signs of functional convergence. In other words, evolution appears to have arrived at similar catalytic solutions multiple times through different genetic routes. For drug developers, this convergence is good news: a compound designed to block the conserved active site of one lipase has a reasonable chance of affecting others, including the pancreatic lipase that matters most for obesity therapy.

Structural modelling brought the sequence data into three dimensions. Superimposition of predicted and experimentally determined structures confirmed that all the analysed enzymes share the classic alpha/beta-hydrolase fold, the architectural scaffold that underpins virtually all lipase catalysis. But the models also highlighted one of the most important and least appreciated features of lipase biology: the lid domain. This mobile structural element swings open and closed over the active site, regulating access for substrates and inhibitors alike. The researchers found that these lid-dependent conformational changes are preserved across the enzyme family, and that the position of the lid dramatically alters what a drug molecule can actually ‘see’ when it approaches the binding pocket.

That insight proved decisive in the docking experiments. Using AutoDock Vina 1.2.0, the team docked orlistat into both open-lid and closed-lid conformations of several lipases, including lipase ITB 2.1, human pancreatic lipase and monoacylglycerol lipase. The results were striking: orlistat bound far more strongly to the open-lid state than to the closed state across the board, confirming that active-site accessibility governed by lid dynamics is a critical determinant of inhibitor potency. Among all the enzymes tested, lipase ITB 2.1 exhibited the most favourable binding affinity for orlistat, a result that immediately flagged the bacterial enzyme as a sensitive and responsive screening target.

Docking alone can be misleading, however, because it captures a single frozen snapshot rather than the dynamic reality of protein-ligand interaction in a watery, thermally jostling cellular environment. To address this, the researchers ran molecular dynamics simulations of 100 nanoseconds for each enzyme-orlistat complex using the GROMACS engine with the CHARMM36 protein force field and CGenFF ligand parameters. The simulations confirmed that all the complexes were stable over the simulated timescale, with the ligand remaining lodged in its binding pocket throughout. Monoacylglycerol lipase and pancreatic lipase displayed the highest overall structural stability, but lipase ITB 2.1 maintained consistent compactness and reliable ligand retention, exactly the qualities one wants in a reproducible screening model. Analyses of root-mean-square deviation, radius of gyration and interaction fingerprints together painted a picture of a firm, durable drug-enzyme engagement.

The crucial test came in the laboratory, where computational prediction met wet-lab reality. Enzymatic inhibition assays measured how effectively orlistat shut down lipase ITB 2.1’s catalytic activity. The kinetics followed classic Michaelis-Menten behaviour, with a maximum velocity of 1428 micromoles per minute and a Michaelis constant of 81 micromoles. Most tellingly, the enzyme was completely inhibited at an orlistat concentration of just 56.25 micromoles, demonstrating exquisite sensitivity to the drug. These experimental values vindicated the docking scores and simulation stability data, closing the loop on a validation chain that stretched from raw sequence all the way to measured biochemistry. Very few candidate screening enzymes are put through such a comprehensive gauntlet before being adopted by the research community.

The implications extend well beyond one enzyme and one drug. A validated, thermally robust, structurally well-characterised lipase model gives medicinal chemists a dependable platform for virtual screening of large compound libraries, for rational drug design and for rapid experimental confirmation of computationally predicted inhibitors. Because lipase ITB 2.1 responds to orlistat with clear, quantifiable kinetics and retains a conserved catalytic architecture shared with human pancreatic lipase, candidate molecules that inhibit it are strong candidates for inhibiting the therapeutic target as well. The integrated workflow demonstrated in this study, spanning sequence analysis, AlphaFold-era structural prediction, docking, 100-nanosecond dynamics and enzymology, also offers a template that other laboratories can replicate for validating model enzymes in entirely different drug-discovery contexts.

There are, of course, caveats and next steps. Lipase ITB 2.1 is a bacterial enzyme, and while its active-site chemistry is conserved, differences in lid architecture, surface properties and physiological context mean that hits identified against it will still require confirmation against human pancreatic lipase and, ultimately, in animal and clinical models. The study’s authors also note that the open-versus-closed lid comparison underscores the need to account for protein flexibility in any screening campaign, a lesson increasingly recognised across computational drug discovery. Nevertheless, by demonstrating that a single enzyme model can pass structural, evolutionary, computational and experimental validation in one coherent framework, the Indonesian team has given the fight against obesity a new and practical weapon: a trustworthy molecular stand-in against which the next generation of fat-blocking drugs can be tested quickly, cheaply and with confidence.

Subject of Research: Structure- and function-based validation of the bacterial enzyme lipase ITB 2.1 as a model for anti-obesity drug screening

Article Title: Lipase ITB 2.1: a structure- and function-validated model for anti-obesity drug screening

Article References: Ma’ruf, I. F., Ernawati, T., Hermawan, F., Akhmaloka, A., Warganegara, F. M., Widhiastuty, M. P., Restiawaty, E., Wiraswati, H. L., Wibisana, A., Mozef, T., Hidayati, N. A., Haryati, T., & Simatupang, D. F. (2026). Lipase ITB 2.1: a structure- and function-validated model for anti-obesity drug screening. Molecular Diversity. https://doi.org/10.1007/s11030-026-11731-y

Image Credits: AI Generated

DOI: 10.1007/s11030-026-11731-y

Keywords: lipase ITB 2.1, obesity, orlistat, lipase inhibition, molecular docking, molecular dynamics, alpha/beta-hydrolase fold, lid domain, pancreatic lipase, drug screening, enzyme kinetics, Indonesia