Enzymology in its Second Century

Enzymology has a long and illustrious history, dating back to the seminal work by Sumner on crystallization of urease and demonstration that enzymes were proteins (as reviewed in ¹) .

Isolating and purifying individual enzymes, followed by determining the enzyme’s properties, has been a mainstay of enzymology for the past 90 years. This type of work is still valuable and remains the backbone of enzymology.

I purified my first enzyme as a college freshman in 1973. At that time, there was no choice but to use native sources of the enzyme. A limited number of chromatography media types were available, and all suffered from slow flow and poor resolution. Complete protein sequences were practically unknown, and temperature and pH optima, and K_m and V_max values on defined small-molecule substrates were the major defining properties that defined the enzyme. Over the past 45 years, enzymology has seen quantum leaps in technology:

Edman degradation made determining protein sequences a tedious, but routine practice, opening up enzymology to asking questions about sequence versus function ².

Determining the sequence of enzymes by DNA sequencing ³.

Cloning of genes to eliminate the need for native sources ⁴.

Improved promoters for high level expression combined with enzyme tags and affinity chromatography ⁵.

Complete chemical synthesis of genes coding for enzymes

High throughput enzyme crystal structure determination ⁶.

The result of these technology leaps is a generally faster, easier route to pure, single enzymes. What is needed, as we approach the start of the second century of enzymology, is a new set of challenges for enzymology. Some of these challenges include:

Natural product production by assembling biosynthetic pathways in vitro.

Degradation of complex natural substrates by single enzymes, mixtures of enzymes, and enzyme complexes such as cellulosomes ⁷.

Non-traditional enzymes including single-turnover enzymes such as Cas9 ⁸.

Enzymology of microbial immune systems ⁹.

Role of glycosylation ¹⁰ and other post-translational modifications on enzyme activity.

Functional characterization of “hypothetical proteins” identified in genomic and metagenomic sequencing ¹¹.

There are many routes forward for enzymology in this dawning new century. Enzymologists should boldly explore new techniques and new collaborations to continue advancing the field.

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