WikiBiomeThe human microbiome encyclopediaRanked matches across titles, topics, categories, and article introductions, filtered to mechanism.
Cambialistic enzymes are enzymes that can function with more than one metal cofactor, switching between metals depending on environmental availability. The term derives from the Latin cambium ("exchange") and describes a remarkable adaptation: rather than being locked i…
Ammonia is a nitrogen-containing product of microbial urease activity. When urease hydrolyzes urea, ammonia and bicarbonate are produced; in the microbial systems covered by WikiBiome, those products can provide nitrogen and raise local pH maier 2019 nickel microbial pa…
Aromatase (CYP19A1) is the cytochrome P450 enzyme that catalyzes the final and rate-limiting step of estrogen biosynthesis — the conversion of androgens (testosterone, androstenedione) to estrogens (estradiol, estrone). It is expressed in the ovaries, placenta, adipose …
Aspirin (acetylsalicylic acid) is a non-steroidal anti-inflammatory drug (NSAID) that irreversibly inhibits cyclooxygenase (COX) enzymes, suppressing prostaglandin synthesis. While widely used as an antiplatelet and anti-inflammatory agent, aspirin carries significant i…
Beta-glucuronidase (β-glucuronidase, EC 3.2.1.31) is an enzyme that catalyzes the hydrolysis of glucuronidated compounds, cleaving the β-1,4-glycosidic bond between a sugar and a glucuronic acid group. In the microbiome, beta-glucuronidase is the key enzyme of the estro…
Beta-lactamases are bacterial enzymes that hydrolyze the beta-lactam ring of penicillins, cephalosporins, and carbapenems, rendering them inactive. They are the most common mechanism of antibiotic resistance and a central concern in the antimicrobial resistance crisis. …
Bile salt hydrolase (BSH) is the microbial enzyme that deconjugates primary bile acids (taurocholate, glycocholate) by cleaving the amino acid (taurine or glycine) from the steroid core. This is the first and rate-limiting step in microbial bile acid transformation — wi…
Catalase is a heme-iron enzyme that decomposes hydrogen peroxide into water and oxygen. In microbial peroxide defense, it acts downstream of superoxide dismutase: superoxide dismutase converts superoxide to hydrogen peroxide, and catalase removes that hydrogen peroxide …
Chitotriosidase (CHIT1) is a human chitinase that degrades chitin — the structural polysaccharide of fungal cell walls, insect exoskeletons, and parasitic helminths. It is the most abundant chitinase in human serum and represents a direct arm of innate nutritional immun…
Cyclooxygenase-2 (COX-2) is the inducible enzyme that converts arachidonic acid to prostaglandin H₂ — the precursor of prostaglandin E₂ (PGE₂), prostacyclin, and thromboxane. Unlike COX-1 (constitutive, homeostatic), COX-2 is transcriptionally induced by nf kappa b duri…
This page unifies the infant formula contamination, pregnancy complications, autism spectrum disorder, necrotizing enterocolitis, and neurodevelopmental toxicity threads around a single organizing insight: metal toxicity is disproportionately severe during specific deve…
Ethylenediaminetetraacetic acid (EDTA) is a synthetic aminopolycarboxylic acid widely used as a chelation agent for heavy metal poisoning, particularly lead. In the microbiome context, EDTA is significant for two reasons: its therapeutic use in metal detoxification and …
Enterohepatic circulation (EHC) is the recycling loop by which compounds—primarily bile acids, conjugated estrogens, conjugated glucuronides, and metabolites of drugs and xenobiotics—are excreted in bile, reach the intestine, undergo deconjugation or dehydroxylation by …
Gamma-aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the central nervous system. In the WikiBiome context, GABA is notable because gut bacteria produce it — certain Lactobacillus and Bifidobacterium species possess glutamate decarboxylase (GAD) e…
The third nickel-dependent enzyme class in human pathogens, after urease and hydrogenase. Glyoxalase I detoxifies methylglyoxal, a reactive and toxic byproduct of glycolysis. While less well-known than urease or hydrogenase as a virulence factor, GloI is emerging as a s…
Histidine is a semi-essential amino acid with a unique property that makes it central to metal biology: its imidazole side chain is one of the strongest biological metal-binding groups, coordinating zinc, nickel, copper, iron, and other transition metals in enzymes and …
Hydrogen sulfide is a gaseous signaling molecule (gasotransmitter) produced by both host enzymes (CBS, CSE, 3-MST) and gut bacteria — primarily sulfate-reducing bacteria (desulfovibrio). Like nitric oxide and carbon monoxide, H₂S has dual roles: physiological signaling …
[NiFe] hydrogenases are the second major nickel-dependent virulence factor class in human pathogens. Less widespread than urease but critical for energy metabolism in gastric, enteric, and intracellular pathogens. The discovery that H. pylori hydrogenase powers CagA tra…
Iron-sulfur (Fe-S) clusters are among the most ancient and ubiquitous metal cofactors in biology, present in all domains of life. These inorganic prosthetic groups -- typically [2Fe-2S] or [4Fe-4S] configurations -- mediate electron transfer, enzymatic catalysis, and re…
The kynurenine pathway (KP) is the dominant route of tryptophan catabolism, accounting for approximately 95% of dietary tryptophan degradation. It produces a cascade of neuroactive, immunomodulatory, and potentially neurotoxic metabolites whose balance determines whethe…
The labile metal pool (LMP) is the fraction of intracellular metal that is bioavailable -- loosely coordinated with small molecules, transiently protein-bound, or truly "free" in solution. This pool is vanishingly small (often <1 free atom per cell for zinc and copper) …
Lipid metabolism — the synthesis, transport, and degradation of fats — is profoundly modulated by both the gut microbiome and metal homeostasis. The microbiome influences lipid metabolism through bile acid transformation, SCFA production, TMAO generation, and direct enz…
Metal sensing is the set of regulatory mechanisms bacteria use to detect intracellular metal concentrations and adjust gene expression accordingly. Because metal ions cannot be synthesized or degraded -- only imported, exported, sequestered, or trafficked -- sensing and…
Metal speciation refers to the distribution of a metal among its possible chemical forms — free ions, complexed with organic or inorganic ligands, bound to proteins, or incorporated into mineral phases. In biological systems, speciation determines everything: a metal's …
Specialized proteins that escort metal ions from their point of entry to specific metalloenzyme targets, ensuring correct metalation in a cytoplasm crowded with competing metal-binding sites. Metallochaperones solve a fundamental problem in metal biology: how does the r…
Protein-based transcription factors that sense intracellular metal concentrations and regulate gene expression accordingly. Metalloregulators are the decision-making layer of bacterial metal homeostasis -- they read the labile metal pool, determine whether a specific me…
A family of small (6-7 kDa), cysteine-rich proteins that bind heavy metals with extraordinary affinity. Metallothioneins (MTs) are the cell's primary chemical defense against metal toxicity -- they sequester cadmium, mercury, lead, and other toxic metals, preventing the…
Mis-metallation is the displacement of the correct metal cofactor from an enzyme or protein by a wrong metal ion, leading to loss of function, gain of aberrant function, or structural disruption. This is one of the most fundamental and pervasive mechanisms of metal toxi…
N-glycosylation is a post-translational modification in which glycan chains are attached to asparagine residues on proteins. This modification is critical for protein folding, cell-cell recognition, and immune system signaling. In the context of host-microbe interaction…
Specialized membrane proteins that import nickel into bacterial cells, supplying the essential cofactor for virulence enzymes including urease, NiFe hydrogenase, and Ni-glyoxalase. Because mammals produce no known nickel-requiring proteins, these transporters represent …
Nickel-glyoxalase (Ni-GlxI) is a bacterial variant of the glyoxalase I enzyme system that depends on nickel as its essential metal cofactor. This enzyme detoxifies methylglyoxal (MG), a toxic glycolysis byproduct that accumulates under glucose fermentation. Unlike the h…
Nickel-urease (urease, EC 3.5.1.5) is a metalloenzyme that catalyzes the hydrolysis of urea (NH₂-CO-NH₂) to ammonia (NH₃) and carbon dioxide (CO₂). The active site contains two nickel ions (Ni²⁺) coordinated by histidine and cysteine residues. Nickel-urease is expressed…
NiFe-hydrogenase (also called [Ni-Fe] hydrogenase or nickel-iron hydrogenase) is a class of enzymes that catalyze reversible hydrogen (H₂) oxidation. The active site contains both nickel (Ni) and iron (Fe) metal atoms arranged in a sophisticated bimetallic cluster. The …
Nitric oxide (NO) is a gaseous signaling molecule with roles spanning vasodilation, immune defense, neurotransmission, and gut barrier maintenance. In the microbiome context, NO sits at the intersection of host physiology and microbial metabolism — gut bacteria both pro…
Oxidative stress is the imbalance between the production of reactive oxygen and nitrogen species (ROS/RNS) and the capacity of biological antioxidant defense systems to detoxify them. It is the single most commonly invoked mechanism across metal toxicology in this wiki,…
Pharmacomicrobiomics is the study of bidirectional interactions between drugs and the microbiome. The gut microbiome is not a passive bystander in pharmacology -- it actively metabolizes drugs, alters their bioavailability, and modulates therapeutic efficacy. Conversely…
Phosphodiesterases (PDEs) are a family of enzymes that hydrolyze cyclic nucleotides (cAMP and cGMP), regulating intracellular signaling cascades. PDE5, the isoform targeted by sildenafil and tadalafil, is best known for its role in erectile dysfunction pharmacotherapy, …
Shotgun metagenomics is a sequencing approach that fragments and sequences all DNA in a sample -- bacterial, archaeal, fungal, viral, and host -- without prior amplification of a specific gene target. Unlike 16S rRNA amplicon sequencing, which identifies "who is there" …
Tryptophan (Trp) is an essential amino acid that the human body cannot synthesize and must obtain from diet. It occupies a uniquely important position at the intersection of neuroscience, immunology, and microbial ecology because it is the sole precursor to serotonin, a…
Urea is the substrate of urease. In the microbial systems covered by WikiBiome, urease hydrolyzes urea to ammonia and bicarbonate; those products can supply microbial nitrogen and help neutralize acidic environments maier 2019 nickel microbial pathogenesis. At a glance,…
The most widespread nickel-dependent virulence factor across human pathogens. Urease is found in at least 40 prokaryotic and 9 eukaryotic pathogenic species, making it the single most important enzyme linking dietary/environmental nickel to infectious disease.
Virulence factors are the molecular tools that enable a microorganism to colonize, invade, evade immune defenses, and cause damage to the host. They include toxins, adhesins, invasins, immune evasion molecules, and metabolic enzymes that provide competitive advantages i…
Zinc-metalloproteases are a large and functionally diverse family of proteolytic enzymes requiring zinc (Zn²⁺) in the active site for catalytic activity. They cleave peptide bonds in proteins, causing tissue destruction, immune evasion, and bacterial dissemination. Majo…