Mapping Enzyme Activity on Tissue by Functional Mass Spectrometry Imaging

Abstract

Enzymes are central components of most physiological processes, and are consequently implicated in various pathologies. High‐resolution maps of enzyme activity within tissues therefore represent powerful tools for elucidating enzymatic functions in health and disease. Here, we present a novel mass spectrometry imaging (MSI) method for assaying the spatial distribution of enzymatic activity directly from tissue. MSI analysis of tissue sections exposed to phospholipid substrates produced high‐resolution maps of phospholipase activity and specificity, which could subsequently be compared to histological images of the same section. Functional MSI thus represents a new and generalisable method for imaging biological activity in situ.

Insights into how development and life-history dynamics shape the evolution of venom

“…This novel method supports the heterogeneous distribution of venom components, including the PLA 2 , and three-finger toxins [ 86 ]. Intriguingly, the distribution of these venom components showed that their abundances are non-overlapping, in which the abundance of three-finger toxins in the posterior region of the gland has limited PLA 2 activity [ 86 ].…”

“…Using a novel mass spectrometry imaging (MSI) method, Hamilton et al [ 86 ] revealed the spatial distribution of venom activity across the snake venom gland. The venom glands of the brown forest cobra ( Naja subfulva ) [ 87 ] are rich in enzymatically active phospholipases A2 (PLA 2 ) and sections exposed to phospholipid substrates produced high-resolution maps of phospholipase activity and specificity [ 86 ]. This novel method supports the heterogeneous distribution of venom components, including the PLA 2 , and three-finger toxins [ 86 ].…”

“…The venom glands of the brown forest cobra ( Naja subfulva ) [ 87 ] are rich in enzymatically active phospholipases A2 (PLA 2 ) and sections exposed to phospholipid substrates produced high-resolution maps of phospholipase activity and specificity [ 86 ]. This novel method supports the heterogeneous distribution of venom components, including the PLA 2 , and three-finger toxins [ 86 ]. Intriguingly, the distribution of these venom components showed that their abundances are non-overlapping, in which the abundance of three-finger toxins in the posterior region of the gland has limited PLA 2 activity [ 86 ].…”

Characterising Functional Venom Profiles of Anthozoans and Medusozoans within Their Ecological Context

“…Therefore, MSI offers the opportunity to analyse peptide mixtures and evaluate peptide localisation for any species. This approach has been applied to the imaging of venom toxins from sea anemones, snakes and centipedes to date [16,25,[140][141][142][143][144]. Identification of venom components directly from MSI spectra, however, remains non-trivial.…”

“…It has also contributed to understanding the variable tissue expression patterns of toxins within order Actiniaria, having been employed to visualise both widely distributed and highly localised toxins in A. tenebrosa [16,25,140]. Taking into account the presence of enzymes within sea anemone venom, the use of MSI as a novel assay to investigate the regulation of enzyme activity also confers considerable utility [144].…”