# Using Heat-Resistant Enzymes to Read DNA Sequences Faster

> This patent describes using a heat-stable enzyme from a bacterium that lives in hot springs to make the process of reading DNA code much more reliable and efficient.

- **Patent:** US 5075216
- **Original title:** Methods for dna sequencing with thermus aquaticus dna polymerase
- **Owner:** Cetus Corp
- **Granted:** 1991
- **Status:** Public domain (expired)
- **Times cited:** 146
- **Field:** biotech, semiconductors

## What it does

The patent improves the Sanger sequencing method, which reads DNA by stopping the building process at specific points using special molecules called dideoxynucleotides. Previously, researchers used enzymes that broke down at high temperatures, causing errors and incomplete readings. By using DNA polymerase from Thermus aquaticus (Taq), an organism that thrives in boiling water, the reaction can be performed at higher temperatures. This helps the DNA strands stay open and prevents them from tangling, leading to much clearer and more accurate results.

## What it does NOT cover

- Does not cover the fundamental Sanger sequencing method itself, only the use of Taq polymerase within it.
- Does not cover the discovery of the Thermus aquaticus organism.
- Does not cover sequencing methods that do not use dideoxynucleotide chain termination.
- Does not cover the use of DNA polymerases derived from organisms other than Thermus aquaticus.

## The clever bit

The inventors realized that the heat-stability of the Taq enzyme, originally prized for PCR, was the perfect solution to the 'secondary structure' problem in DNA sequencing, where DNA strands fold onto themselves and block the reading process.

## Real-world examples

1. Standard Sanger sequencing protocols used in clinical diagnostics
2. Automated capillary electrophoresis DNA sequencers
3. Molecular biology research kits for gene mapping

## Why it matters

This innovation was a critical step in the automation of DNA sequencing, which eventually enabled the Human Genome Project. By making the sequencing reaction robust enough to withstand high temperatures, it allowed scientists to read longer and more complex stretches of DNA without the frequent failures that plagued earlier methods.

## Frequently asked questions

### What does Using Heat-Resistant Enzymes to Read DNA Sequences Faster cover?

This patent describes using a heat-stable enzyme from a bacterium that lives in hot springs to make the process of reading DNA code much more reliable and efficient.

### Who owns patent US 5075216?

Cetus Corp owns this patent, granted in 1991.

### When does this patent expire?

This patent has expired and is now in the public domain — anyone can use the invention freely.

### What is patent US 5075216 cited by?

This patent has been cited by 146 later patents that build on its ideas.

### What problem does this patent solve?

This innovation was a critical step in the automation of DNA sequencing, which eventually enabled the Human Genome Project. By making the sequencing reaction robust enough to withstand high temperatures, it allowed scientists to read longer and more complex stretches of DNA without the frequent failures that plagued earlier methods.

### What does this patent NOT cover?

Does not cover the fundamental Sanger sequencing method itself, only the use of Taq polymerase within it.

**Full plain-English explainer:** https://patentbrief.org/patent/us/5075216/modified-taq-polymerase

**Original patent:** https://patents.google.com/patent/US5075216

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_Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._