What is cutinase?
Cutinase hydrolyses ester bonds in cutin, a polyester component of the plant cuticle. Its accessible active site has also made it important in research on other ester-containing materials.
Cutinase and lipase have overlapping ester chemistry but different substrate-access features. Neither label guarantees broad degradation of all plastics.
The key idea
A surface change is not equivalent to complete polymer depolymerisation.
[3]
Core properties and EC classification
An EC number classifies a catalysed reaction. It does not specify a production strain, amino-acid sequence, preparation purity or operating optimum. Related proteins can perform the same classified reaction, while a commercial activity name may cover several reactions.
· Classification · Accepted activity · Reaction scope
· EC 3.1.1.74 · cutinase · cutin + H 2 O = cutin monomers
· Substrate / system · Chemical distinction · Practical interpretation
· Cutin hydrolysis · Natural polyester substrate · Biological cutinase context
· Small ester assay · Soluble model chemistry · Does not reproduce a solid polymer surface
· Synthetic polyester conversion · Polymer-dependent access · Crystallinity and temperature history matter
[3]
Molecular weight: monomer, dimer or multimer?
A monomer contains one protein subunit; a homodimer contains two copies of the same subunit, and a higher oligomer contains more. A protein domain is a region within a chain, not an additional subunit. Likewise, mixing enzymes in a bottle does not establish that they form a stable molecular complex.
· Property of the named example · Evidence and interpretation
· Molecular weight of the example · Approximately 22.3 kDa for the deposited protein entity (one polypeptide; PDB 1CEX). This is not whole-formulation mass or a measured glycosylated mass.
· Monomer, dimer or multimer? · Monomer, as annotated for PDB 1CEX biological assembly 1.
· Model and experimental resolution · PDB 1CEX; 1.0 Å X-ray diffraction; representative chain A.
· Deposited protein sequence · 214 residues in the experimental entity; unresolved coordinates and biological processing are separate considerations.
The mass above is the deposited polypeptide-entity value. Glycosylation, precursor processing, linkers or omitted domains can change the experimentally observed mass. SDS–PAGE primarily informs denatured subunit size; native assembly needs evidence such as SEC–MALS, analytical ultracentrifugation or an appropriate structural analysis. The viewer shows one selected chain for clarity, not necessarily the complete biological assembly.
[1][2]
FROM MOLECULE TO APPLICATIONA surface change is not equivalent to complete polymer depolymerisation.
Natural sources and fermentation hosts
Fusarium solani and related plant-associated fungi provide classic examples. The model’s organism is also recorded as Nectria haematococca in structural taxonomy.
Fungal fermentation and recombinant microbial expression provide production routes. Engineered polyester-active enzymes can differ substantially from the natural cutinase shown here.
· Term · What it means in this report
· Natural donor of the model · Nectria haematococca mpVI — the organism associated with the displayed protein sequence.
· Expression host of the structural sample · Saccharomyces cerevisiae
· Manufacturing route · Fungal fermentation and recombinant microbial expression provide production routes. Engineered polyester-active enzymes can differ substantially from the natural cutinase shown here.
· Supplied product · Use the linked product documentation for the actual grade, activity assay and declared source. A structural example does not establish the manufacturing organism or purity of the supplied preparation.
[1]
Reaction mechanism and structure–function relationships
A serine–histidine–aspartate catalytic triad forms an acyl-enzyme intermediate. Many classical fungal cutinases have a relatively exposed active site rather than the large mobile lid associated with some lipases. Activity on synthetic polyesters depends on polymer accessibility, crystallinity and enzyme architecture; a cutinase label alone does not establish efficient PET degradation.
THE REACTION, STEP BY STEP
1
Access a susceptible ester bond
2
Form a serine acyl-enzyme intermediate
3
Use water to release hydrolysis products
Cutin ester bonds + water→Cutin-derived monomers and oligomers
Conceptual reaction pathway; the stages describe function rather than atomic geometry.
From active-site chemistry to a useful process
A surface change is not equivalent to complete polymer depolymerisation. Characterise the starting polymer and compare treated and untreated material using soluble-product analysis plus a material measurement. Keep surface area and pretreatment constant when comparing enzymes or doses.
The catalytic mechanism explains which chemical transformation is possible. It does not, by itself, establish the rate in a complex material. Substrate presentation, reaction-medium composition and retention of the active fold determine whether that chemistry can proceed usefully under the chosen conditions. This is why a defined-substrate activity measurement and an application trial provide complementary evidence.
[2][3]
Discovery and scientific milestones
Discovery, purification, structural characterisation and industrial adoption are different historical milestones. The named studies below identify specific contributions; a publication date is not automatically the first discovery of every activity covered by the enzyme name.
1975
Biochemical and historical context
Purdy and Kolattukudy purified and characterised Fusarium cutinases in 1975. These studies connected plant-cuticle hydrolysis with defined enzyme proteins.
[3]1997
Longhi and colleagues: molecular characterisation
The primary study associated with PDB 1CEX is “Atomic resolution (1.0 A) crystal structure of Fusarium solani cutinase: stereochemical analysis.”. The experimental structure links the named protein to a concrete molecular model, allowing its fold, substrate-binding region and assembly to be examined rather than inferred from the general enzyme name.
[2]
Major industrial applications and research uses
Research and development cover textile-surface modification, ester synthesis and polyester hydrolysis. Assess polymer molecular weight, crystallinity and soluble products when evaluating material conversion; surface change alone is not complete depolymerisation.
01
Polyester research
Investigate enzyme-accessible ester cleavage.
Measure success: Measure soluble products and remaining polymer.
02
Textile surfaces
Modify accessible surface chemistry.
Measure success: Assess the required material function.
03
Ester synthesis
Explore suitable non-aqueous or controlled-water reactions.
Measure success: Resolve product identity and side reactions.
A research use, a development-stage process and an established commercial application do not imply the same level of readiness. Match the preparation to the target matrix and required grade, then validate the specific outcome described above. The product links below provide the route from this scientific overview to a defined supplied formulation.
Activity assays and interpreting experimental results
Model esters provide convenient activity measurements, but polymer assays need mass balance and product analysis. Record surface area, temperature, agitation and pretreatment. Soluble oligomer release and total mass loss are different endpoints.
A useful experiment for this enzyme
Characterise the starting polymer and compare treated and untreated material using soluble-product analysis plus a material measurement. Keep surface area and pretreatment constant when comparing enzymes or doses.
· Experimental question · Evidence to collect
· Is the enzyme active? · Measure an initial rate with a defined substrate, blank correction and a stated activity-unit definition.
· Does it work on this material? · Measure soluble products and remaining polymer.
· Is the preparation stable? · Measure residual activity after a specified exposure, separately from activity during the exposure.
· Is the product what you intended? · Assess the required material function.
Keep enzyme loading, substrate amount, mixing, temperature and sampling time explicit. Use a no-enzyme control to capture non-enzymatic changes and a suitable analytical blank for colour, background sugars, peptides or other interfering components. A time course is more informative than one endpoint when the reaction slows, because substrate depletion, loss of activity and product effects can produce similar plateaus.
Reading kinetic and operating data
Compare reported pH and temperature optima only when substrate and assay duration are comparable. An optimum describes the measured rate within an experiment; it is not a guarantee of long-incubation stability. For heterogeneous substrates, changes in accessibility can also affect apparent kinetic behaviour. Cite the protein, substrate and conditions alongside any kinetic constant rather than treating it as a universal property of the enzyme name.
[3]
Common questions
Does every cutinase efficiently digest PET?
No. Protein architecture and polymer accessibility determine performance.
Why test a model ester at all?
It can confirm catalytic activity, but it is only one part of polymer evaluation.
Can mass loss alone establish monomer recovery?
No. Soluble fragments or physical loss can contribute.
Continue exploring
Cutinase for Cutin and Polyester Trials: Surface Change vs Breakdown ↗Lipase deep dive ↗CalB lipase deep dive ↗Phospholipase deep dive ↗
