Homology Modeling & Loop Refinement

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Overview

Even with deep-learning prediction available, template-based modelling remains the better route in several situations: when a close experimental template exists in the exact conformational state you care about, when a specific ligand-bound form must be reproduced, or when a predicted model needs its loops, termini and side chains rebuilt to a usable standard. We build, refine and validate such models and, importantly, state which parts are supported by the template and which are effectively invention.

Schematic: pockets are detected across the whole surface, scored for druggability, and the residues carrying the binding energy are mapped before any screening begins.

Key Advantages

State-Specific Modelling

Where a target adopts distinct active, inactive or ligand-bound states, templates are chosen for the state your project needs rather than for global sequence identity alone.

Serious Loop Treatment

Loops are rebuilt with conformational sampling and energy scoring, with alternative conformations delivered when the loop is genuinely mobile instead of a single arbitrary pose.

Multi-Template Assembly

Different regions can be modelled from different templates where that is better supported, with the boundaries and their justification documented.

Validated Before Delivery

Every model passes geometry, packing and environment checks, and the report identifies regions not reliable enough to support design decisions.

Where This Service Is Used

Building a structure for a target where prediction alone is insufficient or unconvincing

Producing a ligand-bound or specific conformational state for docking and design

Modelling a close orthologue or mutant from an existing experimental structure

Repairing experimental structures with missing loops, disordered termini or poorly resolved side chains

Generating consistent structural models across a protein family for comparative analysis

Methods and Techniques Applied

Template identification by sequence and profile search, with coverage, identity and conformational state assessed together

Alignment construction and manual correction in functionally critical regions, where automated alignment often fails

Single- or multi-template model building with restraint-based or fragment-assembly methods

Loop sampling and refinement with energy scoring, including alternative conformations for mobile loops

Side-chain rebuilding, hydrogen placement, protonation assignment and restrained energy minimisation

Validation with Ramachandran, rotamer, clash and residue-environment analysis, plus comparison with the template

What We Need From You

Target sequence in FASTA, with the isoform, construct boundaries and any tags specified

The conformational state required and any ligand or cofactor that should be present

Preferred templates if your team already has a view on which structure is relevant

The downstream application, which determines how aggressively loops and side chains are refined

What You Receive

Final model in PDB format together with the alignment and template record

Alternative loop conformations where the loop cannot be resolved to a single pose

Validation report covering geometry, packing and per-region reliability

Prepared structure ready for docking or MD, with protonation states documented

Written assessment stating which regions may carry design decisions and which may not

What We Compute and Report

Template coverage, sequence identity and alignment quality per modelled region

Full-atom coordinates with alternative conformations for loops that cannot be resolved to one pose

Per-residue model quality estimates distinguishing design-ready regions from unreliable ones

Geometry and packing validation statistics for the finished model

Binding site quality assessment reported separately from global model quality

Interpretation and Limitations

Computational predictions prioritise hypotheses; they do not independently establish binding, biological activity, therapeutic efficacy, safety or clinical validity. Performance depends on input quality, target class, the structural evidence available and the applicability domain of the selected methods. Scores used for ranking are comparative devices and should not be read as measured quantities. All deliverables are for research use only and are not intended for diagnostic or therapeutic use.

Specifications

Item	Specification	Notes
Typical turnaround	5–15 working days	Extensive loop refinement or multi-template assembly takes longer
Template identity	Best available	Below roughly 30% identity reliability drops sharply and we say so
Loops refined	All missing regions	Ensembles supplied for genuinely flexible loops
Validation	Full geometry report	Delivered with every model

Service Workflow

Step 01

Scientific Consultation

We discuss the objective, the decision it supports and the data you hold. Nothing is quoted before we understand what the result has to answer.

Step 02

Feasibility Review

We check that the data, target class and available structural evidence can support the proposed approach, and say plainly where they cannot.

Step 03

Technical Proposal

Scope, methods, deliverables, timeline and price are confirmed in writing, together with the limitations we expect to report.

Step 04

Computation and QC

The analysis runs on pinned tool versions in a containerised environment, with quality checkpoints and method comparison where that is informative.

Step 05

Report and Follow-Up

You receive the ranked results, the documented methods, the limitations and a proposed validation plan, plus support in interpreting them.

Is This the Right Service for You?

Choose this service when

A close template exists in the specific conformational or ligand-bound state you need

An experimental structure has missing loops, termini or poorly resolved side chains

Consistent models are needed across a protein family for comparative work

Consider another service when

No suitable template exists and the fold itself must be predicted

AI Protein Structure Prediction

The loop is genuinely mobile and its dynamics matter more than one pose

Classical MD Simulation

What Goes Wrong, and How We Handle It

The failure modes that produce confident-looking results which do not survive the next experiment. Each one is designed against rather than discovered afterwards.

Templates are selected for the state the project needs, and the state of each candidate template is stated in the report.

Case Studies

The situation

The only structure of the target had eleven disordered residues directly over the catalytic site, making docking impossible.

What the work involved

Templates with the loop resolved were identified, the alignment was corrected by hand in that region, and the loop was rebuilt with conformational sampling and energy scoring.

What came back

Three distinct loop conformations, two of which left the site accessible. Docking was run against both, and the poses that were consistent across them were prioritised.

Illustrative of the shape this work takes. Details are generalised, no client or target is identified, and scope and outcome vary with the system in question.

Questions We Are Asked Before Scoping

Note: ICDMO delivers computational (in silico) services. Results prioritise hypotheses for testing; they do not by themselves establish binding, biological activity, efficacy or safety. All deliverables are for research use only and are not intended for diagnostic or therapeutic use. Downstream experimental work is scoped separately and executed through qualified partners.

Get in Touch
about Homology Modeling & Loop Refinement

Tell us about the target, the data you hold and the decision the result needs to support. A scientist reviews every enquiry and replies within one business day.

Feasibility reviewed before any scope or price is fixed

Methods, parameters, confidence and limitations in every report

Confidentiality agreement available before data is shared