3507 - Enzymes; prepared enzymes not elsewhere specified or included:

This HTS category, 3507, encompasses enzymes and prepared enzymes that are not specifically classified elsewhere within the Harmonized Tariff Schedule. Enzymes are biological catalysts, typically proteins, that accelerate specific biochemical reactions. This classification includes both naturally occurring enzymes in their crude or purified forms, as well as those that have been modified or prepared for specific industrial or commercial applications, such as in food processing, textiles, or pharmaceuticals.

Distinguishing Chapter 35 from its siblings in Section VI, which includes a wide array of chemical products, is crucial. While other chapters in Section VI might deal with organic chemicals, plastics, or fertilizers, Chapter 35 specifically focuses on albuminoidal substances, modified starches, glues, and importantly, enzymes. Therefore, goods classified under 3507 are primarily defined by their biological catalytic function rather than their broader chemical composition or application.

Within HTS 3507, subcategories exist to further refine classification. For instance, 3507.10.00.00 specifically addresses rennet and its concentrates, a vital enzyme used in cheesemaking. The remaining entries under the "Other" subheading, 3507.90, are reserved for all other enzymes and prepared enzymes not falling under the more specific rennet classification, requiring further breakdown based on their source, preparation method, or intended use to determine the precise tariff treatment.