Table 1. Residues with missing NH resonances in the catMMP12-R5 ¹H-¹⁵N solid state NMR experiment.

Residue No.	Residue Type	Flanking sequences	Secondary structure Element
110	R	RKH	Loop
119	N	RINNY	Loop
121	Y	NNYTP	Loop
122	T	NYTPD	Loop
124	D	TPDMN	Loop
147	L	TPLKF	Loop
157	A	GMADI	Loop
166	G	ARGAH	Loop
168	H	GAHGD	Loop
172	H	DFHAF	Loop
176	G	FDGKG	Loop
185	F	HAFGP	Loop
186	G	AFGPG	Loop
188	G	GPGSG	Loop
189	S	PGSGI	Loop
190	G	GSGIG	Loop
201	F	EDEFW	Loop
206	H	TTHSG	Loop
207	S	THSGG	Loop
208	G	HSGGT	Loop
209	G	SGGTN	Loop
211	N	GTNLF	Loop
213	F	NLFLT	Helix
228 (active site ligand)	H	LGHSS	Loop
229	S	GHSSD	Loop
236	M	AVMFP	Loop
241	K	TYKYV	Loop
254	D	ADDIR	Helix

The resonances assignment reported in the bmrb under the accession code 6444⁴² has been used for the interpretation of the spectra. Also for GFP some resonances could not be observed, again maily in proximity of charged residues and loops (Fig. 3 and Table 2).